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CHAPTER 5
INTERVENTION STRATEGIES
Dan LUNGU, Cristian ARION
Structural Safety for Natural Hazard Research Centre,
Technical University of Civil Engineering Bucharest, Romania
5.1 GENERAL & TERMINOLOGY
The value of heritage cannot be measured simply in terms of price. Conservation professionals and
decision-makers increasingly must confront economic realities.
Policy makers decisions are many times outside the domain of conservation practice for the cultural
heritage.
The PROHITECH project seeks the intervention strategies for historical buildings taking into accounts
the economic and cultural background of the specific countries.
The following web sites contains criteria and methodology for seismic rehabilitation of historical heritage
buildings: www.unep-wcmc.org, www.wmf.org, www.worldbank.com www.iccrom.org, www.getty.edu,
www.international.icomos.org.
Who is implementing the “project”?
The project strategy should contain informations that can be used by building owners, public clerks,
architects, engineers and policy makers in order to decide on the adequate solutions for necessary
rehabilitation interventions on constructions.
Implementing the concept of a target performance, the rehabilitation should allow a comprehensive
understanding of the parameters essential in the analysis that can ultimately provide the optimal
intervention solutions.
Who is responsible?
The responsibility of safeguarding the existent individual building falls on the owners, while in the
case of public constructions that exhibit a high level of vulnerability the responsibility extends to the
authorities.
Planning the retrofit of historical buildings before an earthquake strikes is a process that requires
teamwork of engineers, architects, code officials, NGO, administrators and authorities.
Policy development should also include consideration of other urban and environmental factors
affecting the future of a place/location of building.
What is the target?
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The two major goals of the seismic rehabilitation/strengthening in historic buildings are life safety and
the protection of historical value of the building. Because rehabilitation should be sensitive to historic
materials and the building's historic character, it is important to put together a team experienced in
both seismic requirements and historic preservation. Team members should be selected for their
experience with similar projects, and may include historians, architects, engineers, code specialists,
contractors, and preservation consultants. Because the typical seismic codes are written for new
construction, it is important that both the historians & architect and structural engineer be
knowledgeable about historic buildings and about meeting building code equivalencies and using
alternative solutions.
The rehabilitation programs might be active i.e. directly intended for strengthening of the building and
passive i.e. due to the change of occupancy of the buildings.
The reinforcement of the historical buildings to meet new construction requirements often, can destroy
much of the historical building's appearance integrity and value.
Important preservation principles
Three important preservation principles should be kept in mind when undertaking seismic retrofit
projects:
• Historical materials should be preserved at the largest extent possible and not replaced
wholesale with other new materials in the process of seismic strengthening;
• New seismic retrofit systems, whether hidden or exposed, should respect and should be
compatible to the architectural and structural integrity of the historical building;
• Seismic work should be "reversible" to the largest extent possible to allow future removal for
the use of future improved systems.
While seismic upgrading work is often more permanent than reversible, care must be taken to preserve
historical materials to the historical appearance of the building.
In addition to the above principles, the general aim of building conservation is to preserve the cultural
significance of the place where the building is culturally aggregated. Places of cultural significance
should be safeguarded and not left at risk in a vulnerable state.
The different intervention works are defined in various manners documents from various countries, as
well as in general literature, TABLE 5.1.
TABLE 5.1 Terminology for seismic rehabilitation of historical buildings
Oxford popular English
FEMA 2004, and
dictionary
The Australia ICOMOS charter for the conservation
of places of cultural significance
modifying a place to suit the existing use or a suitable for new use or
Adaptation
proposed use
conditions
the operations which maintain the building as it is
Conservation
today, even if limited interventions are accepted to
improve the safety levels
the rebuilding or renewal of any parts of the Make or become secure and
Consolidation
construction (of some elements or an assembly of strong
elements) with the purpose of obtaining an
enhanced structural capacity; for example, highresistance capacity, enhanced stiffness, better
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Examination
Intervention
Maintenance
Preservation
Repair
Reshaping
Rehabilitation
Restoration
Reconstruction
Strengthening
FEMA 2004, and
The Australia ICOMOS charter for the conservation
of places of cultural significance
ductility
the visual part of an investigation that excludes
material testing, structural analysis, structural
testing, and other more sophisticated investigative
techniques
a concept that involves standards/norms regarding
consolidation, repair and reshaping of structural
and/or non-structural elements
continuous protective care of the fabric/aggregate
and setting of a place, and is to be distinguished
from repair
maintaining the fabric/aggregate of a place in its
existing state and retarding deterioration
rebuilding or renewal of any damaged or faulty part
of the construction to obtain the same level of
resistance, stiffness and/or ductility with the those
previous to its degradation
Repair involves restoration or reconstruction.
the rebuilding or renewal of any parts of the
construction resulting in the change in function or
in the occupancy
rebuilding or renewal of a damaged construction in
order to ensure the same level of functioning,
similar to the that previous to the degradation of the
building
returning the existing fabric/aggregate of a place to
a known earlier state, by reassembling existing
components without the introduction of new
material
Oxford popular English
dictionary
enter a situation to change its
course or resolve it
process
of
something
maintaining
keep safe, unchanged, or in
existence
put into good condition after
damage; make amends
redevelop
condition
into
restore to a normal life or good
condition
bring back to its original state
returning a place to a known earlier state and it is reconstruct; restore
distinguished from restoration by the introduction original form
of new material into the work.
judicious modification of the strength and/or
stiffness of structural members or structural systems
to improve their performance in future earthquakes.
Strengthening generally includes increasing the
strength or ductility of individual members or
introducing new structural elements to significantly
increase the lateral force resistance of the structure.
On occasion, strengthening can also involve making
selected structural members weaker to improve the
interaction of the structural members and prevent
premature failure of a weaker adjacent member.
The diagram of used terminology is presented in FIGURE 5.1.
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certain
to
its
value
strengthening
100
requirements
maintenance
ageing without
maintenace damage
repair
restoration
ageing with
maintenace
time t
FIGURE 5.1. Value alteration diagram of a building
5.2 INTERVENTION SOLUTIONS AND CRITERIA FOR SEISMIC UPGRADING &
REHABILITATION OF CONSTRUCTIONS
The intervention solutions must rely on cost-benefit analyses and take into account their socioeconomic impact on society.
An obvious requirement is to minimize as much as possible the disturbance of the owners of the
building during the building rehabilitation.
The financial resources available decisively influence the intervention solutions for the particular
purposes, including labor work capacity, equipments, materials, duration of the work etc.
It is also compulsory to have alternative strategies for intervention and to evaluate the decrease in
building vulnerability with various strategies.
The following excerpts from various international organizations should be considered for intervention
decisions.
Examples of international organizations are given in TABLE 5.2.
Traditional techniques and materials are preferred for the conservation of old building aggregates.
However, modern techniques and materials, which offer substantial conservation benefits, may
sometimes be also appropriate.
Restoration and reconstruction should reveal significant cultural aspects of the place.
Restoration is appropriate if there is sufficient evidence of an earlier state of the fabric.
Reconstruction is appropriate only a place is incomplete through damage or alteration, and where
there is sufficient evidence to reproduce an earlier state of the fabric. In rare cases, reconstruction
may also be appropriate as part of a use or practice that retains the cultural significance of the place.
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Demolition of significant fabric of a place is generally not acceptable. In some cases minor demolition
may be appropriate as part of conservation. Removed significant fabric should be reinstated when
circumstances permit.
TABLE 5.2. International organizations related to historical heritage preservation
http://www.international.icomos.org
ICOMOS is an international non-governmental organization of professionals,
dedicated to the conservation of the world's historic monuments and sites.
World Heritage
http://www.unep-wcmc.org
ICCROM
Via di San Michele 13, Rome, Italy
Tel: +39 06 585531
www.iccrom.org
International Centre for the Study of the
Preservation and Restoration of Cultural Property
http://www.getty.edu
The Getty Conservation Institute
http://www.wmf.org
World Monuments Fund is the foremost private, non-profit organization
dedicated to the preservation of historic art and architecture worldwide through
fieldwork, advocacy, grant making, education, and training
The intervention strategy and the intervention techniques must take into account the following criteria:
(i)
(ii)
(iii)
(iv)
(v)
(vi)
Seismic hazard level at the construction site;
Characteristics of the building intended use (architectural constrains, original occupancy of the
building, building structure, technical equipments within the building, etc);
Building safety as a response to daily activities, mainly related to the seismic safety (structural
vulnerability, vulnerability of non-structural elements, appliances or/and equipments, building
exposure or value, etc.;
Required level for building performance (life safeguarding, immediate occupancy after
earthquake, preventing building-collapse, etc);
Economical criteria, including insured & reinsured value of the building;
Technological capability available at the site.
5.2.1 The Repair and Strengthening Design Process
Even though the main aim of this workpackage is the reviewing of intervention strategies, some basic
principles on current approaches to damage assessment and definition of vulnerabilities of structural
types will be cited for completeness.
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5.2.1.1 Criteria of Repair and Strengthening
A post earthquake evaluation of the seismic parameters of the region and the individual sites is
required for the earthquake affected region and structures. The definition of the seismic parameters for
the region is a prerequisite for successful accomplishment of the repair and strengthening of
damaged/undamaged structures. The study should include the expected maximum acceleration of
bedrock for different return periods, amplification factors and to propose adequate time histories and
average spectra for design of repaired structures. For more important structures, group or typical
structures it is necessary to determine the seismic parameters for the considered sites and to perform
field, soil investigations and geophysical studies to be used as input design parameters.
The definition of seismic criteria comprises the correlation of the seismic force design parameters with
the structural characteristics in terms of strength, deformability, ductility, etc.
Each country or governmental area should establish its own criteria based on specific conditions
related to the seismology and probable seismic events of the region. The criteria for repair and
strengthening should preferably not be fully encompassed by the current building code for new
construction, although showing respect to its provisions.
The designer must use established criteria or Codes and Regulations of the area as the minimum
standard for repair and strengthening projects. For selected projects such as historical structures, the
designer may have to use criteria in excess of the established ones, based on the particular
circumstances regarding the project. The designer may also have to establish criteria or methods to
assign strength values to traditional materials whish are not covered by modern Building Codes or
Regulations.
5.2.1.2 Structural investigations
During the preliminary investigation, the nature and general degree of damage is determined. In order
to design repair and/or strengthening measures, it is necessary to perform additional investigations and
gather supplemental data while fully utilizing the preliminary investigation ones.
Documents regarding the original construction should be compiled to the extent that they are available.
This includes the designs, drawings, specifications, construction details, data on original construction
material strengths, foundation and soil condition data, previous repairs or alterations, coeds under
which the original design was prepared, etc. The information gathered should be compared with the
actual structure to confirm that it was built in conformance with that information. Deviations should be
noted and recorded. If information is not available or considered untrustworthy, field measurements
and observations must be taken into account to verify the characteristics of the original construction.
More specifically, the problems that arise while treating rehabilitation tasks of historical buildings
concern the laborious work demanded for evaluating material characteristics and structure of bearing
elements, as well as the lack of relevant written material. It is often required studying specific
structures under loading conditions which are considered probable to have occurred, instead of
designing on purpose of fulfilling safety demands under well-defined loading cases. In addition,
interpretation of the actual structural performance is expected to be based on existing damage, the full
record of which is non achievable.
Completion of the detailed site inspection, which begun in the preliminary investigation, must be
accomplished. This operation is an essential and important phase in the process of designing repair and
strengthening measures. Damage due to seismic forces most often appear in structural elements as
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columns, shear and infill walls, beams, beam-column joints, staircase towers, floor slabs and the
connection between floors and walls and foundations. Each structural member must be inspected and
the damage or lack of damage must be recorded, sketched and photographed. Damage and location of
non-structural elements should also be recorded and present status, characteristics and strength of
original construction materials should be estimated during the additional investigation.
5.2.1.3 Damage evaluation and selection of a repair and strengthening solution
Utilizing the investigation data which has been documented and the criteria for repair and
strengthening, the designer must typically evaluate the damage, perform analysis to determine why the
damage occurred, and develop alternative schemes to repair and/or strengthen the structure. These
alternative schemes must be evaluated and the most appropriate solution should be selected.
The engineer must first analyze the damaged structure and thoroughly understand the causes of
damage occurrence. The force resistant paths in the building must be determined, explaining why
certain members sustained damage while others were practically untouched. It must be determined
whether the structure suffered due to discontinuities in strength or stiffness, due to torsional moments
within the structure, due to hammering with adjacent structures or due to improper connections or
details. The effects of non-structural elements such as infilled walls and appendages on the structural
performance must be considered. It must be determined if members failed due to shear, compression,
tension, flexure, bar anchorage, etc. This analysis is essential before any repairs can be assigned.
Calculations and analysis must be performed in order to evaluate the existing strength and stiffness of
the damaged structure. The decision of the need to strengthen the structure will generally follow these
analyses. If the repaired structure without strengthening conforms to the design criteria, then
strengthening will generally not be required. If the repaired strength is less than the requirements of the
criteria, the strengthening will generally be desirable in addition to repairing the damage.
Based on results obtained by this analysis, alternative solutions for repair and/or strengthening can be
determined for evaluation of their feasibility. Imagination and ingenuity should be exercised by the
designer utilizing professional experience, as the best and most economical solution is seldom the first
one conceived. Analysis for every alternative scheme must be performed to evaluate the effects of the
strengthening measures and provide a reasonable basis for comparison among them.
It must be recognized that despite the specific design criteria used, possible “weak links” in the
structure can be detected during the analytical procedure. A future earthquake strong enough to cause
damage will result in some elements of the repaired structure exceeding their yield strength and
sustaining inelastic response. With a thorough understanding of the potential “weak links” in the
structure, the designer can propose repair and strengthening measures whish will improve the
response of the structure in future earthquakes. The repair and strengthening measures should establish
an improved structure for seismic performance by avoiding irregularities in plan, abrupt changes in
stiffness between floors and elements subjected to shear or brittle failure. The effects of strengthening
elements added to the structure must be carefully evaluated to insure that they will not cause increased
damage in a future earthquake.
Conclusively, in order to select one solution for implementation, apart from the factors discussed
above, the feasibility evaluation of alternative solutions must include the following aspects:
• Compatibility with the functional requirements of the structure
• Feasibility of construction, including availability of materials, construction equipment and
personnel with specialized training and the ability to implement the solution
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•
•
•
Economical considerations
Sociological considerations
Aesthetics
5.3 OPTIONS FOR INTERVENTION STRATEGY
The strategy of interventions for improvement of the seismic performance of a structure or for the
reduction of seismic risk might contain technical or/and managing approach.
The technical strategies approach use the interventions on the bearing structure for the repair of
possible deficiencies, on the increase of strength and stiffness of the structure, on the increase of the
deformation assumption capacity, on the increase of the energy dissipation capacity and the reduction
of seismic requirements. The basic intervention selection criterion is the limitation of damages caused
to the primary and the secondary structural elements to acceptable levels for a given performance
level.
There are also managing strategies that can be taken into consideration during the design of
interventions.
Managing strategies comprise:
(a) the decision of realizing interventions while the building remains in use or of evacuating it
until the end of the strengthening works,
(b) the acceptance of the existing seismic risk of the building and the omission of interventions or
the alteration of its use in a way that renders the seismic risk acceptable,
(c) the demolition of the existing building and its substitution with another,
(d) the realization of the proposed interventions progressively in a very large time margin or the
taking of temporary strengthening measures until the replacement of the structure,
(e) the accomplishment of interventions on the external of the building in order to minimize the
negative consequences for the inhabitants or in the internal in order not to change the
characteristics of its external aspect.
Managing strategies should be co-assessed by engineers and owners in order to select the suitable
intervention strategy.
Generally, the best solution for a building is related to the taking of decisions of a managing and
technical nature.
5.3.1 Technical Strategies
The technical strategies might apply when the structure should dispose a complete system for seismic
load assumption, able to limit deformation in extents that correspond to acceptable damage levels for
the targeted structural performance level.
The main parameters which define the efficiency of the seismic loading bearing system are: (a) the
mass, stiffness, damping and configuration of bearing and not bearing structural elements, (b) the
deformation capacity of bearing and not bearing structural elements and (c) the energy and character of
the seismic excitation imposed to the structure.
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Deciding the intervention strategy on building in terms of structure resistance, deformation and
ductility performance, as well as in terms of non-structural elements performance should be made
explicit through the following relation:
SEISMIC REQUIREMENT~ ≤ CAPACITY
The measures of intervention for the accomplishment of the above relation are:
(i)
Reducing seismic requirements;
(ii)
Improving the mechanical characteristics of the construction;
(iii)
Combining modalities: (i) and (ii).
In other words, the options the designer has are either to ensure an elastic behavior of the structure or
to increase the hysteretic energy through plastic behaviour which involves the degradation of the
structural elements.
The strategy of improving a structure through local interventions is applied to structures which,
although dispose the basic elements of an adequate seismic loading bearing system, lack of some
constructional details which are necessary for the system optimization and the ensuring of the required
functionality. The deformation capacity of such a structure may be adequate in comparison with the
given seismic requirements, all the same before reaching this deformation it is probable that local
damages in different locations of the structure occur. The most usual defects which are to blame for
such local damages are the inadequate seating length at abutment locations of precast elements and the
inadequate anchoring or connection between structural elements, either primary or secondary. Local
interventions aiming at reforming these defects would allow a satisfactory structural behavior. Very
often the strategy of local interventions is used in combination with other strategies in order to reach
an adequate structural behavior.
5.3.1.1 Reducing seismic requirements
Reducing seismic requirements can be achieved by the following methods:
(i) Reducing resistance requirements. The modalities of reducing seismic inertia forces developed in
the structure can be identified by analysis of the structural elastic response acceleration spectrum. The
objective is to stay away, as much as possible, from the maximum amplification of the spectrum by
altering the characteristics of the structure.
Reduction of resistance requirements may also be achieved through a reduction of building mass. This can
be obtained by eliminating unnecessary weights: getting out one or several storeys, reducing the weight of
partition walls, replacing a heavy roof with a light one etc.
(ii) Reducing drift requirements. The reduction of drift requirements may be generally achieved by
reducing the natural period of building, either by increasing the stiffness or by decreasing the mass of
the construction.
5.3.1.2 Improving the mechanical characteristics of the construction
Improving the mechanical characteristics of the construction can be done by, FIGURE 5.2.:
a) Increasing the stiffness to lateral forces. Increasing stiffness certainly reduces the effective
drifts under values given by the lateral forces;
b) Increasing of the plastic deformation capacity, i.e. increasing of ductility;
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c) Increasing the resistance capacity. In many situations of insufficient ductility increasing the
ductility is difficult to be achieved in practice and seems to be much easier increasing the
building resistance;
d) Increasing the dissipation/damping capacity. In several cases increasing the dissipation
capacity can be achieved by elements that may be sacrificed on purpose. The infilled walls
(partitions) may be specially designed to fit this purpose. In most cases the intervention on a
structural characteristic will inevitably modify other properties that the structure has. The
increase in stiffness, for example, may enhance the resistance of the structure as well as the
decrease in drift and ductility requirements.
FIGURE 5.2. Concept of seismic retrofit and seismic performance upgrading of existing building
5.3.1.3 Choice of intervention systems
The seismic strengthening methods can be classified as follows, as far as their target is concerned:
1.
In case the target is the increase of stiffness and structural strength, the most effective
method is the addition of walls in the existing frames. What follows is the method of adding
truss bracings, the method of adding walls as an extension of existing columns and the use of
composite materials.
2.
In case the target is the increase of plasticity, the method that is recommended is the
application of jacketing on a number of selected columns, as well as the use of composite
materials.
3.
In case the target is the simultaneous increase of strength, stiffness and plasticity of the
structure, any seismic strengthening method can be used taking into consideration the
required degree of increasing each of the above mentioned characteristics. In case that the
necessary increases are very high for all three characteristic, it is generally inevitable the
addition of new vertical elements.
5.3.2 Repair & Strengthening of Existing Buildings
As the general awareness of the earthquake risk increases, and standards of protection for new
buildings become higher, the safety of the older, less earthquake-resistant construction becomes an
increasingly important concern. In many earthquakes, damage is concentrated in the older building
stock, while recently constructed buildings stiller comparatively lightly. The problem can be expected
to diminish over time if improved standards of new construction can be achieved, because the
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proportion of unsafe buildings in the total building stock will diminish. This is true particularly where
there is a high rate of turnover of the building stock. But such cases are rare; in many industrialized
countries the rate of new building construction is only about 1% per annum, and even in more rapidly
developing areas with sustained growth rates of 8% and more, the total number of older buildings does
not diminish very rapidly.
Indeed, rather than being taken out of use, the older building stock is increasingly being modified and
adapted, sometimes in ways which significantly increase the loading or reduce its inherent resistance
to earthquake ground shaking. And where old buildings are not being modified, lack of maintenance
may lead to decay of already weak and poorly integrated structures, resulting in a continual decline in
earthquake resistance possibly made worse by the cumulative effect of low levels of damage in
previous earthquakes.
For all these reasons, strengthening existing buildings is assuming increasing importance in earthquake
regions.
For most types of buildings, strengthening is a cheaper way of bringing earthquake resistance up to
acceptable levels than rebuilding; depending on the situation and construction type, costs of
strengthening typically range from 5% to 40% of the cost of a new building. Careful consideration
needs to be given to the type of strengthening best suited to achieve the desired safety level. Factors
which need to be taken into consideration in deciding whether to strengthen, and which method to use,
will include:
• The required level of structural resistance;
• The general structural form and any changes needed;
• The materials and degree of connection in the existing structure;
• Foundation conditions and the effect of strengthening on them;
• The effect of strengthening on the appearance and functioning of the building;
• Required strengthening of non-structure and services;
• The time during which the building will be unusable;
• The cost of the work.
The main objective in strengthening is to achieve a structure, which satisfies the principles of good
earthquake-resistant design. The actual methods used are different for different types of structure.
5.3.2.1 Strengthening unreinforced masonry buildings
Many cities, towns and villages in earthquake zones consist primarily of unreinforced masonry
buildings of a great variety of types and ages which experience has shown to have poor resistance
against earthquakes. Damage to masonry structures usually takes the form of tension and/or shear
cracks caused by imposed deformations e.g. differential settlement, excessive lateral forces e.g. from
arch thrusts or incipient bursting due to buckling of ashlars or expansion of rubble fill in structures
which consist of relatively thin ashlars faces with a core of rubble and mortar.
The principal sources of the weakness of these buildings are:
• Low-strength masonry units and mortar inadequately bonded together.
• Insufficient interconnection between inner and outer leaves of external walls, insufficient
connection at the junctions of perpendicular walls.
• Insufficient rigidity of floor and roof slabs in their own plane, and inadequate connection
between these slabs and the bearing walls.
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These weaknesses are frequently compounded by the deterioration of the structure due to weathering
and rot, and to extensive structural modification during the lifetime of the building.
According to the weaknesses identified in particular cases, strengthening may involve any or all of the
following interventions:
• Modifying the plan form of the building to improve symmetry, improving the connections
between perpendicular walls;
• Strengthening or replacing floor and roof structures, and improving their connection with the
load-bearing walls;
• Strengthening the walls themselves;
• Strengthening the foundations.
The range of techniques available is wide, and details depend on the type of masonry involved.
Common strengthening techniques include:
• Stiffening existing wooden floors and roofs by covering them with a thin layer of reinforced
concrete;
• Insertion of reinforced concrete ring beams into the inner face of external walls at floor and
caves level to tie vertical and horizontal elements together;
• Extensive strapping of masonry walls to each other and to slabs using both horizontal and
vertical steel straps;
• Strengthening of walls (mainly when cracked) by cement injection or by adding a thin layer of
cement render reinforced with steel mesh on either side of the wall;
• Adding plywood sheathing;
• Strapping parapets.
Where repair and strengthening by these means is not considered feasible, an alternative is to introduce
a new independent concrete frame to carry the earthquake loads, and attach the masonry to it.
Methods of evaluating the earthquake resistance of existing unreinforced masonry building have been
developed both in California and New Zealand. These methods can also be used to assess the
effectiveness of proposed strengthening interventions, and so to consider the cost-effectiveness of
strengthening as against alternative mitigation measures such as reconstruction or change of use.
5.3.2.2 Strengthening reinforced concrete buildings
The need for strengthening reinforced concrete buildings has become more urgent in recent years in
countries where recent earthquake damage has indicated that the resistance requirements in previous
codes were inadequate or where buildings have been found to be below code standard. The principal
causes of weakness in reinforced concrete buildings are:
• Insufficient lateral load resistance, as a result of designing for too small lateral loads.
• Inadequate ductility, caused by insufficient confinement of longitudinal reinforcement,
especially at beam-column or slab-column junctions.
• A tendency to local overstressing due to complex, and irregular geometry in plan and elevation.
• Interaction between structure and non-structural walls resulting in unintended torsional forces
and stress concentrations.
• Weak ground floor due to lack of shear walls or asymmetrical arrangement of walls.
• High flexibility combined with insufficient spacing between buildings resulting in risk of
neighboring structures pounding each other during shaking.
• Poor-quality materials or work in the construction.
Unrepaired damage from previous earthquakes may also be a reason for requiring strengthening.
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The principal objective in most strengthening interventions is to increase the lateral load resistance of
the building; usually increasing the ductility of the structure will be an additional objective. The
strengthening may also involve removing or redesigning non-structural walls which may affect the
performance of the building, and sometimes the strengthening effect may be achieved by removing
load from a structure (by, for example, reducing the number of stories). For tall buildings on soft soil
deposits, an increase in stiffness may also help to improve a building's performance by reducing its
natural period to a value below that of the subsoil. Often the intervention may require simultaneous
strengthening of the foundations. The principal technical options for improving the lateral loadcarrying ability of existing reinforced concrete structures include:
• Adding concrete shear walls,
• Buttressing,
• Jacketing,
• Adding cross-bracing or external frames.
Adding Shear Walls
The most common method of strengthening of reinforced concrete frame structures is the addition of
shear walls. These are normally of reinforced concrete, or may exceptionally be of reinforced masonry.
In either case, they are reinforced in such a way as to act together with the existing structure, and
careful detailing and materials selection are required to ensure that bonding between the new and
existing structure is effective. The addition of shear walls substantially alters the force distribution in
the structure under lateral load, and thus normally requires strengthening of the foundations.
Buttressing
Buttresses are braced frames or shear walls installed perpendicular to an exterior wall of the structure
to provide supplemental stiffness and strength. This system is often a convenient one to use when a
building must remain occupied during construction, as most of the construction work can be performed
on the building exterior. Sometimes a building addition intended to provide additional floor space may
be used to buttress the original structure for added seismic resistance. Buttresses typically require the
construction of foundations to provide the necessary overturning resistance. Even considering the extra
foundation costs, the cost of buttressing an occupied building may be substantially lower than that for
interior shear walls or braced frames. The aesthetic impact and the availability of building space
adjacent to the existing building are obvious factors affecting choice of this solution.
Jacketing
An alternative technique is to increase the dimensions of the principal frame members by encasing the
existing members in new reinforced concrete. The technique is known as jacketing. Adequate
reinforcement of the new encasing concrete can increase both strength and ductility, and concrete
damaged in a previous earthquake can be replaced at the same time. Again careful consideration needs
to be given to achieving an adequate bond between the existing and new concrete. Jacketing of beams
is much harder than columns; jacketing the beams and columns may be ineffective if the beam/column
joint is inadequate, and retrofitting joints is also difficult. Jacketing may be a viable option where a
significant improvement is available from increasing the strengthening and ductility of some or all of
the columns, without substantial intervention to the beams and joints. It may be attractive where there
are architectural difficulties in adding shear wails. Jacketing is a valuable technique when complex or
deep foundations make the change in the lateral load-bearing system required by a shear wall system
impossible or very costly.
Addition of Cross-bracing
Both of the above techniques involve major interventions to the structure. An alternative technique,
involving a less drastic intervention and smaller increase in foundation loads, is the addition of steel
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cross-bracing to increase lateral load resistance. Tin's generally also involves the strengthening of
adjacent columns, which will have to carry increased axial loads, although this is offset by a reduction
in column moments and ductility demand. Strengthening of columns may be achieved by the addition
of an external steel cage surrounding each of these columns. The addition of steel bracing considerably
alters the appearance of a building, but is particularly suitable for comparatively low-cost
strengthening of buildings which have not been damaged in a previous earthquake.
Other Methods
Other methods sometimes adopted to improve the performance of reinforced concrete buildings in
earthquakes include the addition of separate external frames (ATC-40), or the removal of one or more
storeys to reduce the lateral load. New techniques such as bonding of steel plates to the concrete frame
have been proposed but are as yet little tested. In rare instances, base isolation has been used to protect
the superstructure from the ground shaking, but this is very expensive. The addition of supplemental
damping devices is becoming increasingly used as a retrofit measure for concrete frame buildings.
This is generally suitable for special cases; it would not be recommended unless a high level of the
relevant engineering expertise is available. In a few cases strengthening through the use of advanced
fiber-reinforced plastic (FRP) has been used. While this method has the drawback of cost, it offers the
advantage of quick installation, minimum disruption, and no weight increase in the structure.
5.3.2.3 Repair and strengthening of historical buildings
In what way do monumental buildings differ from other buildings that constitute the world’s
architectural heritage? The international framework of principles for the protection and restitution of
historical buildings is known as the “International Charter of Venice”.
The International Charter of Venice was drafted in May 1966 on the occasion of the second
international conference of architects and building technicians involved in the restoration and
maintenance of monuments that was held in Venice. It consisted of a re-examination of a similar
Charter of 1931 and summarized the experiences and lessons of almost twenty years of intense
postwar restoration activity. For obvious reasons the creators of the Charter were almost entirely
concerned with medieval and later buildings that were in use immediately before the war and not with
the special case of monumental buildings of Greco-Roman civilization. Nevertheless, the Charter of
Venice has become widely accepted because of its concise, uncomplicated character. Speaking about
structural restoration, from all the 16 articles included in the Charter, the followings have a significant
meaning:
Article 2: The conservation and restoration of monuments must have recourse to all sciences and
techniques, which can contribute to the study and safeguarding of the architectural heritage.
The involvement of structural engineering faculty in the restoration practice is fully justified from this
article.
Article 9: The process of restoration is a highly specialized operation. Its aim is to preserve and reveal
the aesthetic and historic value of the monument and is based on respect for original material and
authentic documents. It must stop at the point where conjecture begins, and in this case moreover any
extra work, which is indispensable, must be distinct from the architectural composition and must bear
a contemporary stamp. The restoration in any case must be preceded and followed by an
archaeological and historical study of the monument.
Article10: Where traditional techniques prove inadequate, the consolidation of a monument can be
achieved by the use of any modern technique for conservation and construction, the efficacy of which
has been shown by scientific data and proved by experience.
14
Another principle, deriving indirectly from the Charter of Venice, is the reversibility that is the
acceptance of the possibility of the restitution of a monument to the condition it was in prior to the
intervention. This principle stems from the view that a monument is a source of scientific evidence and
from the premise that mistakes may occur during the execution of the work. It takes as its starting
point the intention to preserve the monument as a source of evidence after the work is completed and
also to ensure that any mistake is rectifiable.
Historical buildings constitute a case of special importance. A distinction has to be made between:
(1) Historical monuments and
(2) Historical urban centers.
Each is valued for different reasons and the strengthening techniques necessary to retain those values
arc different, and have different costs and constraints. It is important in planning the repair of older
buildings to consider which approach and level of budgeting suits each building. Usually strengthening
of historical structures will be done as a result of minor damage from an earthquake, or they may have
been damaged in other ways. In either case, the techniques for repair and strengthening are the same.
Historical Monuments
Historical buildings are valued for their cultural associations and interesting physical construction. In
restoration and strengthening, the physical fabric of the structure must remain essentially the same as
before the earthquake. Strengthening elements that are added should be unobtrusive and. where
possible, reversible, i.e. removable by future renovators. This type of restoration work requires
specialist skills and is expensive. There may be only a few buildings for which this sort of expense can
be justified. Restoration and strengthening techniques used on historical monuments include:
• Dismantling damaged masonry and reassembling it with improved mortar and concealed
reinforcement (e.g. metal cramps, reinforcing bars, mesh, etc.).
• Addition of concealed tension bars, as anchor bolts, ring beams, corner ties, splay members,
arch chords, and other structural connections. These maybe drilled through masonry using
extended bit drills, capped and grouted into place.
• Internal grout or chemical injection into wall cores where poor-quality rubble has to be
stabilized and bonded without altering the external wall finish.
• Strengthening or stiffening foundations.
There may often, however, be some conflict between the desire for reversibility and the effectiveness
of the intervention. Grouting can be gravity fed or pressure injected, but is irreversible and often
unpopular with renovators.
Historical Urban Centers
The historical centers of many earthquake-prone cities consist of dense residential and commercial
districts whose buildings are usually of unreinforced stone or brick masonry, much altered in
unrecorded ways over the centuries and often in poor condition. Although they represent a valuable
and irreplaceable part of the urban heritage, they are often under threat from general decay and
deterioration and from the pressure for redevelopment in addition to the earthquake risks they face.
To date little has been done to protect any of such buildings from future earthquake damage, and
upgrading strategies are needed which will fulfill the sometimes conflicting criteria of life safety for
occupants and functional upgrading, limitation of damage from future earthquake, and limitation of
alteration to the fabric and appearance of the buildings. Criteria governing the choice of upgrading
strategy for historical centers are: first, that interventions should make a significant improvement to the
earthquake resistance of the buildings in a way which is both identifiable and measurable; secondly,
that interventions should cause only very limited alteration to the external appearance of the building;
and thirdly, that interventions should be consistent with existing programs of upgrading for the
15
buildings in terms of cost, appropriate techniques and the process of design and management. Repair
and strengthening techniques suitable for use in these situations include:
• Use of steel tie rods passing through the floors and external walls with external anchorage
plates or bars to connect the walls and the floors together.
• Improving the stiffness of floors in their own plane by adding new timber members - for
instance, two layers of floorboards laid perpendicular to each other or by cross-bracing with
steel straps. The monolithic floors can themselves be made into strengthening diaphragms for
their supporting walls by chasing in and casting skirting beams around the edge of the floor.
• Jacketing the walls by application of layers of wire mesh on each face, tied together through
the wall at intervals and covered with a layer of dense plaster.
Where upper storeys are badly cracked and lower floors are relatively sound, the upper storey may be
demolished, a reinforced concrete ring beam cast on top of the remaining wall, and a new identical
upper storey constructed. New masonry should be reinforced and may be in solid brick, high-quality
concrete block work, or cut stone. Original wall thicknesses should be retained, and a reinforced
concrete ring beam at roof level should top all walls. In reconstruction, the plan of some buildings - for
example, 'L'-shaped plans - may be compartmented into interlocking rectangular structural units, by
means of ring beams and cross-ties, for greater seismic rigidity.
In cases of moderately damaged walls with elaborate stucco decoration work, it may be possible to
save the wall and its original decoration by using cement injection grout injected into the core of the
wall. This should only be used in conjunction with extensive 'stapling', i.e. drilling and grouting steel
reinforcing bars as connector reinforcements between walls and from walls to floors.
The skills needed for repair and restoration of the buildings of historical urban centers are general
building skills. Techniques of grouting, stapling and mesh reinforcement are relatively straightforward
to learn and can be carried out by almost any building professional. Skilled craftwork is needed for
repair and for renovation of any original interiors that owners wish to preserve.
5.3.2.4 Materials and construction techniques
Repair materials should be compatible with the original construction. This applies to the stone, as well
as the mortar.
Repair and strengthening techniques are conveniently considered under the headings of the defects
they are intended to remedy.
The selection of a suitable solution for repair or strengthening of a structure presupposes that the
engineers involved have a satisfactory knowledge on materials and techniques available for such
interventions. Conventional materials of construction are often insufficient at providing solutions, even
though they still play a major role in the procedure. The need of using new materials and innovative
technologies combined with modified traditional ones arises very often. As a result, there would be
established a system of quality control and cooperation insuring between traditional and new materials.
Replacement and Strengthening of wall Intersections: Wall intersections are particularly vulnerable to
earthquake damage, resulting frequently in large vertical cracks or separations as the walls are
insufficiently interconnected and lack adequate strength to allow proper interaction. Considering the
basic weakness of masonry construction under earthquake conditions, repair procedures are most often
combined with a local strengthening of the wall intersection.
16
Stone stitching, or adding stones across the crack is a method, which can be used. A reinforced
concrete corner column properly tied into the intersecting walls could be added to strengthen the wall
intersection.
Strengthening Walls by Confinement with steel sections: structural steel sections can also be used to
strengthen masonry walls. Steel sections can be quickly installed and are often used when urgency of
repair and strengthening is necessary. Depending on conditions, light steel sections may also be more
readily available than shotcreting equipment or other suitable alternatives. The steel sections must be
attached to tie beams or belts and the horizontal diaphragms at both top and bottom.
Strengthening Rubble Core Stone Walls with Injection: Strengthening of rubble core stone masonry
structures can be summarized as connecting the walls of the building at the level of the floor and roof
by steel ties on both sides of the wall, anchored at their ends, and by grouting the walls with cement
emulsion or other adhesives. This method of strengthening stone structures can be used in combination
with other procedures such as adding shear walls or strengthening shear walls by jacketing of some
wall parts within the structure. In this case, when new elements are introduced into the structure, the
foundation structure should be checked and strengthened, if necessary.
Steel profile jacketing: steel profile skeleton jacketing consists of four longitudinal angle profiles
placed one at each corner of the existing reinforced concrete column and connected together in a
skeleton with transverse steel straps.
Jacketing with steel profiles (angles and straps) is used at the strengthening of separate members,
mainly columns. The joint beam-to column is difficult to strengthen by this technique. Jacketing by
steel encasement is implemented by gluing of steel plates on the external surfaces of the original
members. This technique does not require any demolition, it is considerably easy for implementation
and there is a negligible increase in the cross section size of the strengthened members.
Steel encasement: Steel encasement is the complete covering of the existing column with thin steel
plates. Special measures must be provided for fire and corrosion protection.
Steelwork for structural restoration
Steelwork can be conveniently used for the consolidation of all kind of structures, both old and new,
made of all common constructional materials, i.e. masonry, timber, reinforced concrete and also steel
itself. In the case of consolidation of historical structures, the use of steel gives further advantages to
the designer who has undertaken this delicate operation. The use of steelwork is widely used in many
consolidation operations which are framed in restructuring.
Comparing to the use of metal sheets for structural reinforcement, the alternative application of FRPs
introduces some significant advantages, such as the excellent weight to strength properties, the
material availability in an unlimited length, the comparatively easier installation and the strength
against corrosion. These advantages render composite materials to be a very attractive alternative
proposal.
Glued Metal or Fiber Reinforced Polymer straps
The use of glued straps of steel or Fiber Reinforced Polymers, for strengthening of reinforced concrete
elements, is nowadays a very popular technique due to the ease of its implementation. The traditional
way of practice suggests the use of steel plates but the implementation of FRP straps has been growing
competitively.
17
Shear connectors – anchors
Metal connectors which are anchored on existing concrete elements can act either as studs or as
anchors, depending on the type of load applied. Studs are subjected to shear stress while anchors are
stressed by axial load. There is a variety of industrialized connectors which are anchored on concrete
elements in a mechanical or chemical way. Chemical fixing of connectors, constituting the most
popular choice in practice, is almost always performed by epoxy resins.
Anchorage and welding of new reinforcement bars
Anchorage of reinforcement bars on hardened concrete is accomplished in chemical way, by the use of
an epoxy resin.
FIGURE 5.3 indicates that by adding wing wall increases strength and ductility, ductility is increased
remarkably by RC jacketing, steel jacketing, FRP wrapping and installing seismic slit.
FIGURE 5.3. Strengthening effect in the case of columns observed in structural test
Repairing Gravity Load Capacity of Beams: Steel rods can be used for improving the shear resistance
of damaged or undamaged beams. If load reversals are anticipated, four-sided jacketing is the preferred
method of strengthening. Steel plate reinforcement is a new technique which can be used for beams
subject primarily to static loading to improve their shear strength or midspan flexural strength. This
procedure is not recommended for beams subject to cyclic loading due to earthquakes.
FRP jacketing: The implementation of this kind of materials results in the increase or, even better, the
alteration of bending, shear and axial strength of the member on which they are applied. The use of
FRPs should generally be avoided when the bedding conditions are unknown or poor, there is in
progress a significant corrosion of the reinforcement bars or there is no reinforcement ensuring the
plastic behavior of the member to be strengthened.
Among the most important advantages of the use of composite materials for structural repair and
strengthening, in comparison to relevant traditional methods, the following ones can be stated:
• Insignificant repair is required in the work site. The evacuation of the area is not necessary
and the annoyance to the users is minimal. The preparation of the elements to be strengthened
is small and brief.
• The application of composite materials is simple.
18
•
•
•
•
•
•
The dimensions of the strengthened structural element remain practically unaltered, due to the
small thickness of the composite material.
The placing of composite materials is feasible even when there are working space restraints.
The weight of composite materials is small and for their placing no heavy or specific
equipment is required.
Composite materials can be coated and colored according to the aesthetical needs of the work.
The architectural characteristics of the structures remain practically unaltered.
The application cost of composite materials is analogous to that of the traditional
repair/strengthening methods.
In FIGURE 5.4 is presented a comparison study based on structural tests regarding the strengthening
methods applied to the RC frames. It is indicated an 3.5 to 5.5 times increase in strength in case of
infilling wall. 0.6 to 1.0 times in strength and a little bit increased ductility can be seen in case of
infilling wall compared with monolithic RC wall.
FIGURE 5.4. Strengthening effect observed in structural test
Introduction of new structural elements/systems: New vertical trusses can be constructed with steel
members, cast-in-situ reinforced concrete members or a combination of the two. If reinforced concrete
members are used, all members should be confined with closely spaced ties for their full length to
provide adequate member ductility.
Concentrically braced frames: This traditional form of bracing is, of course, widely used for all kinds
of construction such as towers, bridges, and buildings, creating stiffness with great economy of
materials in two-dimensional trusses or three-dimensional space frames. Concentrically braced frames
are constructed from steel, timber, and concrete and composite forms are frequently met such as timber
beams and columns with steel diagonals.
Eccentrically braced frames: This system conforms in part to the requirement for good earthquake
design of failure mode control, insofar as post-elastic behavior of the frame is largely confined to
selected portions of the beams and sudden failure modes are suppressed.
Hybrid structural systems: The most common of these hybrid systems are those in which momentresisting frames are combined with either structural walls or diagonally braced frames. While hybrid
systems are often unavoidable and can provide good seismic resistance, care must be taken to ensure
that the structural behavior is correctly modeled in the analysis.
19
FIGURE 5.5. Strengthening effect observed in structural test
5.3.2.5 Foundations
It may be desired that the strengthening of the foundation is not required in seismic retrofit pf
buildings. In general, strengthening of foundation shall be performed only when the retrofit scheme is
simple, practical, cost effective, and reliable for drastic improvement of seismic performance. Also,
when adverse effects to the structural performance of building concerned is expected in future due to
settlement of ground, negative friction of pile, and liquefaction of sandy soil at the time of earthquake,
we have to improve the soil performance appropriately.
FIGURE 5.6.Seismic strengthening method of pile foundation
20
FIGURE 5.7. Construction methods as measures against liquefaction
5.3.3 Passive Control of Structures—Energy Isolating and Dissipating Devices
5.3.3.1 Introductory remarks
Earthquake ground motions impart kinetic energy into structures, and the principles of specific
structural forms for earthquake resistance control the location and extent of the damage caused by this
energy. This philosophy can be extended beyond specific structural forms to any means which may
further protect the structure by reducing the amount of energy which enters it.
The family of earthquake protective systems has grown to include passive, active and hybrid (semiactive) systems as shown in FIGURE 5.8. Passive systems are the best known and these include seismic
(base) isolation and passive (mechanical) energy dissipation. Isolation is the most developed member of
the family at the present time with continuing developments in hardware, applications, and design codes.
Passive seismic control strategies are based on the reduction of energy, which may affect a structure in
case of earthquake events. Some well known approaches make use of frictional, plastic or other energy
dissipating behavior of special devices.
Modern structural protective systems can be divided into three major groups:
- Seismic Isolation
Elastomeric Bearings
Lead Rubber Bearings
Combined Elastomeric and Sliding Bearings
Sliding Friction Pendulum Systems
Sliding Bearings with Restoring Force
- Passive Energy Dissipation
21
Metallic Dampers
Friction Dampers
Viscoelastic Solid Dampers
Viscoelastic or Viscous Fluid Dampers
Tuned Mass Dampers
Tuned Liquid Dampers
- Semi-active and Active Systems
Active Bracing Systems
Active Mass Dampers
Variable Stiffness and Damping Systems
Smart Materials
By considering the actual dynamic nature of environmental disturbances, more dramatic improvements
can be realized. New and innovative concepts of structural protection have been advanced and are at
various stages of development. Consequently, some new engineering techniques for modifying the
structure to achieve better earthquake resistance are available, and can be expected to become more
widely used in the future. The most important of these techniques are base isolation and the use of
energy absorbers.
FIGURE 5.8. Family of earthquake protective systems
5.3.2.2 Isolation from seismic motion
The principle of isolation is simply to provide a discontinuity between two bodies in contact so that the
motion of either body, in the direction of the discontinuity, cannot be fully transmitted. The
discontinuity consists of a layer between the bodies which has low resistance to shear compared with
the bodies themselves. Such discontinuities may be used for isolation from horizontal seismic motions
of whole structures, parts of structures, or items of equipment mounted on structures. Because they are
generally located at or near the base of the item concerned, such systems are often referred to as base
isolation, although the generic term seismic isolation is preferable.
The layer providing the discontinuity may take various forms, ranging from very thin sliding surfaces
(e.g. PTFE bearings), through rubber bearings a few centimeters thick, to flexible or lifting structural
members of any height. To control the seismic deformations which occur at the discontinuity, and to
provide a reasonable minimum level of damping to the structure as a whole, the discontinuity must be
associated with energy-dissipating devices. The latter are also usually used for providing the required
22
rigidity under serviceability loads, such as wind or minor earthquakes. Because substantial vertical
stiffness is generally required for gravity loads, seismic isolation is only appropriate for horizontal
motions.
The soft layer providing discontinuity against horizontal motions cannot completely isolate a structure.
Its effect is to increase the natural periods of vibration of the structure, and to be effective the periods
must be shifted so as to reduce substantially the response of the structure. Clearly, the shape of the
design spectrum, the fixed base period, and the period shift are the three factors which determine
whether base isolation has any force-reducing effect (or. indeed, the opposite!).
The location of the isolating devices should obviously be as low as possible to protect as much of the
structure as possible. However, cost and practical considerations influence the choice of location. On
bridges it is generally appropriate (to isolate only the deck where isolation from thermal movements is
required anyway. In buildings the choice may lie between isolating at ground level, or below the
basement, or at some point up a column. Each of these locations has its advantages and disadvantages
relating to accessibility and to the very important design considerations of dealing with the effects of
the shear displacements on building services, partitions, and cladding, TABLE 5.3.
TABLE 5.3. Advantages and disadvantages of base isolation function of the location in buildings
Location
Advantages
Disadvantages
- May require cantilever elevator
- Minimal added structural costs
Bearings located at
- Separation at level of base isolation is pit
bottom of first story
simple to incorporate
columns
- Base of columns may be connected by
diaphragm
- Easy to incorporate back-up system
for vertical loads
- May require cantilevered
- No sub-basement requirement
Bearings located at
elevator shaft below first floor
- Minimal added structural costs
top of basement
level
- Base of columns connected by
columns
- Special treatment required for
diaphragm at isolation level
internal stairways below first
- Back-up system for vertical loads
floor level
provided by columns
- Special consideration required
- No sub-basement requirement
Bearings located at
for elevators and stairways to
- Basement columns flex in double
mid-height of
accommodate displacements at
curvature and therefore may not be
basement columns
mid story
required to be as stiff as for bearings
- No diaphragm provided at
located at the top or bottom
isolation level
- Difficult to incorporate backup system for vertical loads
Bearings located at
- No special detailing required for - Added structural costs unless
sub-basement required for
sub- basement
separation of internal services such as
other purposes
elevators and stairways
a
separate
- No special cladding separation details - Required
(independent) retaining wall
- Base of columns connected by
diaphragm at isolation level
- Simple to incorporate back-up system
for vertical loads
23
5.3.3.3 Analysis concepts of damage controlled structures
Two design concepts:
- The old aseismic design has been based upon a combination of strength and ductility. For small,
frequent seismic disturbances, the structure is expected to remain in the elastic range, with all stresses
well below yield levels. In the case of major earthquake a traditional structure is expect to respond
non-elastically.
Total deformation of the structure: ∆ ≡ ∆f ≡ ∆d
∆f - Elastic deformation of beam and
columns. These structural system
could deform elastically until
1/100 inter story deformation angle.
∆d = Elastic and plastic deformation of
dampers
Building structure
Primary structure
To support vertical loads
Seismic members
To absorb earthquake energy
Beam
Damper
Column
FIGURE 5.9. Idealized structure
24
- The design engineer relies upon the inherent ductility of buildings to prevent catastrophic failure,
while accepting a certain level of structural and nonstructural damage. This philosophy has led to the
development of aseismic design codes featuring lateral force methods and, more recently, inelastic
design response spectra. With these approaches, the structure is designed to resist an “equivalent”
static load.
Small/medium earthquake
Large earthquake
Q
Frame
Old
concept
Q
Frame
δ
δ
Elastic
Q
Q
New
concept
Frame
Inelastic
Damper
δ
Elastic
δ
Inelastic
Q
Frame
Q
Damper
δ
δ
Elastic
Inelastic
5.3.3.4 Seismic isolation using flexible bearings
The most commonly used method of introducing the added flexibility for seismic isolation is to seat
the item concerned on either rubber or sliding bearings. The energy dissipators (dampers) that must be
provided may come in various forms. In addition, all-in-one devices, incorporating both isolation and
damping, are used, namely lead-rubber and high damping rubber bearings. The most effective device,
the lead-rubber bearing, is discussed below.
The lead-rubber bearing (Robinson and Tucker, 1977) is conceptually and practically a very attractive
device for seismic isolation, as it combines all of the required design features of flexibility and
deflection control into a single component. It is similar to the laminated steel and rubber bearings used
for temperature effects on bridges, but with the addition of a lead plug energy dissipator. Under cyclic
shear loading the lead plug causes the bearing to have high hysteretic damping behaviour, of almost
pure bilinear form. The high initial stiffness is likely to satisfy the deflection criteria for serviceability
limit state loadings, while the low post-elastic stiffness gives the potential for a large increase in period
of vibration desired for the ultimate limit state design earthquake.
Further developments in seismic isolation are going on. One such development is an improvement to
both the Rubber Isolation Bearing and to the Lead Rubber Bearing, consisting of a centre-drive to the
top and bottom of the bearings. The “centre drive” approach has two advantages; first it allows a
greater displacement to height ratio and second it provides increased damping capacity at large
displacements, thus providing some of the additional damping needed for resisting “near fault fling”.
5.3.3.5 Rocking structures
As well as the methods described in the preceding sections, the flexibility required to reduce seismic
response may be obtained by allowing part of the structure to lift during large horizontal motions. This
mechanism is referred to variously as uplift, rocking, or stepping, and involves a discontinuity of
contact between part of the foundations and the soil beneath, or between a vertical member and its
25
base. The good performance of many ordinary structures in very strong ground shaking can only be
explained by rocking having beneficially occurred during the earthquake. However, despite apparently
favorable results, such structures have not yet been enthusiastically adopted in practice. This is
probably due to continuing design uncertainties regarding factors such as soil behavior under rocking
foundations in the design earthquake, the possible overturning of slender structures in survivability
events, or possible impact effects when the separated interfaces slam back together.
With the addition of energy absorbers the above hazards are lessened, and utilization of the
advantageous flexibility of uplift has been put to practical effect in completed constructions.
5.3.3.6 Energy dissipators for seismically-isolated structures
In the preceding sections on isolation methods, a number of energy dissipators (dampers) were
presented having been used with seismically-isolated structures, namely:
(1) Lead plugs, in lead-rubber bearings.
(2) Tapered steel plate cantilevers.
(3) Steel torsion-beam.
A variety of other devices have been investigated which are also suitable in this situation:
(4) Lead extrusion devices.
(5) Flexural beam dampers.
5.3.3.7 Energy dissipators for non-isolated structures
As discussed above, energy-dissipating devices are an essential component of seismic isolation
systems, and they also may be used to reduce seismic stresses in non-isolated structures. Various forms
of energy-dissipating devices have been developed for such structures.
Energy dissipators in diagonal bracing
Diagonal bracings incorporating energy dissipators control the horizontal deflections of the frame
and also the locations of damage, thus protecting both the main structure and non-structure. A number
of devices to be connected to diagonal steel bracing show high energy-absorbing capabilities, such as
the lead extrusion damper also used in base isolated structures.
Energy dissipation in bolted beam-column joints
If bolted joint interfaces are designed to permit controlled sliding rotations in earthquake motion, not
only is energy dissipated, but damage is limited or eliminated.
Element for earthquake protection (used at NPP in Romania) made by GERB
The system is effective against forces in both the orizontal and vertical directions. These elements are
maintenance free. Spring elements may provide local elasticity and attract a great extent of the seismic
26
energy. In many cases they represent the most flexible part of the structure. Viscodampers, installed
beside the spring elements, have the task to absorb the kinetic energy. They serve as a displacement
limitation of the structure and the devices
As passive structural control systems begin to see an increased acceptance within the earthquake
engineering community, strong research efforts have been shifted towards the development of semiactive structural control systems. For the sake of completeness, it is worth mentioning that a semiactive control system may be defined as a system which typically requires a small external power
source for operation and utilizes the motion of the structure to develop the control forces, the
magnitude of which can be adjusted by the external power source. Control forces are developed based
on feedback from sensors that measure the excitation and/or the response of the structure. The
feedback from the structural response may be measured at locations remote from the location of the
semi-active control system.
Semi-active control systems maintain the reliability of passive control systems while taking advantage
of the adjustable parameter characteristics of an active control system (requiring a large power source
for operation of electrohydraulic or electromechanical actuators which supply control forces to the
structure). Semi-active systems which are currently under research worldwide include stiffness control
devices, electrorheological dampers, magnetorheological dampers, friction control devices, fluid
viscous dampers, tuned mass dampers and tuned liquid dampers.
It has to be noted that usually it is meaningful to apply a combination of methods or particular
techniques in order to achieve the best solution, economically and technically. It is also worth
mentioning that many times, the intervention method which is selected as the most suitable is not
technically feasible, in terms for example of creating enormous demands for foundation alterations or
functionality problems when the structure returns in use. The legislative framework which is set by the
state tries to combine the “desirable” with the “feasible” and constitutes an issue of a wide political
decision.
In recent years new technologies have been used. Passive control and/or base-isolation methods are
now widely used for earthquake protection of buildings and their contents. A state of the art example
report on new technologies is that of Japan Society of Seismic Isolation, JSSI, K.Kasai 2004.
27
Devices of Passive control systems
Viscous
粘性ダンパー
Oil
オイルダンパー
Viscoelastic
粘弾性ダンパー
せん断，流動抵抗
Shear/Flow
Resist.
Panel,
Box,
Cylinder
面型，
箱型，
筒型
流れ絞り抵抗
Flow
Resist.
Cylinder
筒型
せん断抵抗
Shear
Resist.
Cylinder,
Panel,
etc.
筒型，面型，
その他
F = C ⋅ u& α
F = C1 ⋅ u& or C 2 ⋅ u&
F = K (ω ) ⋅ u + C (ω ) ⋅ u&
F
F
u
Steel
鋼材ダンパー
塑性履歴抵抗
Axial/Shear
Yielding
Cylinder,
Panel,
etc.
筒型，面型，
その他
F = K ⋅ f (u )
F
F
u
u
u
Framing types of passive control systems
FIGURE 5.10. Passive Control Scheme for Mitigating Seismic Damage to Buildings and Equipments
(From K. Kasai, Tokyo Institute of Technology, Japan, 2004)
28
FIGURE 5.11. Examples of configuration of passive control systems
(From K. Kasai, Tokyo Institute of Technology, Japan, 2004)
29
FIGURE 5.12. Examples of configuration of passive control systems
(From K. Kasai, Tokyo Institute of Technology, Japan, 2004)
30
5.3.4 Conclusive Remarks
It is very well known, especially from recent evidence, that historical constructions are by far the most
vulnerable form the seismic point of view, demanding the definition of urgent strategies for the
protection of the cultural heritage from seismic hazard.
Within the current practice in the field of seismic rehabilitation, the methodologies for seismic
upgrading of constructions can be based on either strengthening of structural elements or control of
seismic response. Strengthening systems described in details previously, most commonly adopted, are
based on traditional approaches but adopt the concept of Reversible Mixed Technologies (RMT).
As already known, the concept of RMT can be exploited through the use of both innovative materials
and special devices purposely conceived for the enhancement of seismic performance. Concerning
innovative materials, most suitable are metal materials. New metal-based technologies, indeed, ensure
an increased safety level under any load condition, with an overall cost comparable with or lower than
the one required by traditional options. At the same time, they allow the existing configuration of the
construction to be preserved as much as possible, and this turns to be very important in applications in
the monumental field. Eventually, the use of metals is also environmentally friendly, as such materials
can be easily removed and recycled at the end of their operational life-time.
Ultimately, the application of more advanced and sophisticated solutions, including active, semi-active
or passive systems, has been proposed for the reduction of seismic vulnerability of existing buildings.
5.4 COUNTRY SEISMIC LEGISLATION & ACTIONS FOR SEISMIC INTERVENTION ON
CONSTRUCTIONS
5.4.1 Seismic Risk Management Legislation and Actions
5.4.1.1 Algeria
Algeria has always been subjected to an intense seismic activity, which has resulted in many losses in
human lives and caused significant material damages that has each time, disturbed if not blocked, the
development activities of the country for a number of years. The recent major earthquake of 2003 with
about 5 Billions of US dollars damages and 2300 losses of lives and the one that stroke the region in
1980 inducing more than 2600 deaths and damaging 70% of the region are clear examples of the
seismic vulnerability of the country which, in a period of 20 years, has witnessed more than 9
earthquakes of magnitudes exceeding 5.4 on the Richter scale. Yet, the country has not developed clear
intervention strategies and has not developed a seismic culture for the population to live with.
Education syllabuses do not contain much about the nature of earthquakes, their consequences, and
how should the population behave when these geological phenomena occur.
It is thus important that Governments set up intervention strategies according to their abilities and
means at their disposal in the aim of managing the disaster when the seismic hazard strikes.
Intervention strategies at a wider scale consist of making people aware of the risk well in advance.
Such awareness is best transmitted to the population through education. These intervention strategies
should be guided by laws and regulations based on the work of technicians and experts. Prevention and
mitigation measures are very important intervention strategies that should be considered before the
disaster strikes in order to alleviate the risk consequences.
31
The construction act should be carried out according to specific engineering requirements set up by
expert engineers and architects in a planned land for use. Indeed, land use planning is as important as
the technical engineering requirements for buildings that are expected to absorb the seismic shock
without great damages and losses of lives.
Disaster preparedness is a very important intervention strategy, which makes the population aware of
the risk by learning from past disasters or from probable scenarios of seismic hazards. Governments
and political authorities have a great role in inculcating the seismic risk education to the population
and making them prepared at any time. The same governments and political authorities should be able
to implement the planned measures put in place in the preparedness phase in a short time. This disaster
response includes emergency relief measures such as health, food, water, sanitation, shelter, logistics
and supply, security, etc.This response should be ensured for a maximum number of people affected
before re-establishing gradually the services. The rehabilitation and reconstruction stage should start
immediately in order to get the population to normal life with the promotion of social and economical
aspects.
1980 Chlef earthquake
The 1980 earthquake that hit the region of Chlef had a magnitude of 7.3 on the Richter scale and came
after a period 26 years from a previous less stronger one which hit the same region in 1954 with a
magnitude of 6.7. The devastating nature of this 1980 earthquake, which is classified amongst the
major earthquake disasters of the 20th century had slashed away 70% of the region and made evident
the lack of preparedness of the country to cope with natural disasters of this kind.
This earthquake was however the occasion for the Algerian authorities and the population as a whole
to learn lessons from what has happened. An open seismic training center was there for everybody to
get trained and know about these natural hazards. The technical bodies and civil engineering research
institutions from all over the world precipitated to the accidental site to learn from the catastrophe.
Among the recommendations that were retained to be implemented, the following points deserve to be
recalled:
- Sustained effort for training and information
- Setting up of procedures for normalisation and homologation of building materials
- Tightening up of the procedures for granting agreements for intervention in the building sector
- Tightening up of the control in the building sector (at the design office and at the construction
site)
- Generalisation of the seismic hazards and microzoning studies
- Installation of networks of seismic equipment to record seismic characteristics when they strike
- Elaboration of a code for repair and strengthening of damaged constructions
- Elaboration of a seismic code for the building sector
- Creation of a research center for para-seismic studies
However, the seismic code that has come out after the 1980 earthquake was considered as must only
for official and collective buildings and the private and individual houses continued to be designed
without taking into considerations the seismic regulations, which were not vulgarised in design offices
and insufficiently taught at universities. The control was not in anyway tight and the para-seismic
construction could not succeed in the absence of a follow-up body specially designated by the political
authorities with a full decision power at his disposal. This laxity in considering seriously the seismic
design regulations and improving the quality of workmanship on sites is greatly responsible for what
has happened in the 2003 earthquake that hit Boumerdes and Algiers; the lessons was not learned from
the 1980 earthquake; let’s hope that it is after what has happened in the 2003 earthquake and the
similar type of collapses that were recorded for constructions built after the 1980 earthquake.
32
5.4.1.2 Belgium
In case of a seismic event, the “Crisis Centre” of Belgium and the “Royal Meteorologic Institute” has
to deal with the occurring problems. Nevertheless, Belgium doesn’t possess a general strategy to be
used in case of seismic event.
The local authorities are responsible for the rescue interventions and expertises after a natural disaster.
So, after the earthquake of Liège 1983, it is the security service of Liège who was in charge to
expertise all the damaged buildings.
For each damaged buildings, quick checks were done as:
- Verification of the building stability;
- Verification of the electric equipments;
- Verification of the gas pips;
- Check for cracks in the chimney (to avoid problems with the CO2 gas).
These checks were done directly after the earthquakes and took about 20 days. After this first
verification, more detailed investigations were performed for more damaged buildings.
The damages caused to the buildings needed reparations for a total amount of 75 million euro. So, the
Belgium authorities decided to subsidize investigations to estimate the seismic risk in Belgium and to
find solutions, which could decrease the amount of damages in case of a seismic event. Here below are
mentioned two of the conducted investigations:
- A first project dedicated to the estimation of the seismic risk in a 4km² area in Liège and
conducted by the University of Liège.
- A second project aiming at investigating the behaviour of “non-designed” family houses under
seismic loading. This project conducted to the publication of a technical document proposing
simple and low cost solutions for improving the behaviour of such buildings under seismic
loading.
5.4.1.3 Egypt
'Le Service des Antiquites d’Egypte’, was set up in 1859 to control and to organize the activities
related to Egyptian Antiquities. In 1971, it was replaced, by the "Egyptian Antiquities Organization
(EAO), which more recently, in 1994, was replaced by the "Supreme Council of Antiquities' (SCA).
In 1985, the EAO published the program of its policy (National Heritage: Challenge and Response:
1982-1985). The program focused mostly on restoration of (Islamic) historical buildings noting that
more than 1000 Islamic monuments have perished since 1882 and that the budget for restoration and
conservation was minimal. It reported that more than 500 Islamic monuments are in ruins and noted
that the situation was worsening.
Deterioration problems were defined related to: rising of subsurface water, changes in loads affecting
the foundations, pollution, increasing population density and lack of maintenance, expansion of
housing and lack of public awareness. Recently earthquakes are considered.
Current Institutional Organization and Functions of SCA
The SCA is a department of the Ministry of Culture. The current organizational chart of the SCA
reveals a highly centralized authority headed by the Minister of Culture. The everyday operations of
the SCA are entrusted to a secretary general.
33
The main divisions of the SCA Include, the secretariat, two main divisions are heading to
Egyptian/Greco-Roman monuments, and with Islamic/Coptic monuments, and three other divisions
concerned with museums, projects, and funding. In addition, the council supervises the Nubia Fund
(which administers the funds remaining from the UNESCO Nubia Campaign). These divisions are all
based in Cairo, presiding over smaller regional divisions.
These regional units subdivided as follows:
·
Upper Egypt and the Oases
·
Middle Egypt
·
The Delta, Sinai and the Mediterranean coast
·
Cairo and Giza
Each of these regional units administered from capital centers in turn oversees local inspectorates. The
regional units include specialized group concerned with ownership and properties, documentation, and
excavations.
By law, SCA is the main public institution concerned with monument conservation and controlling all
restoration projects in Egypt. However, other conservation efforts may be carried out by other
government organizations such as the Ministry of Waqfs, involved in restoring mosques and Islamic
monuments. Restoration may also be carried out through private initiatives or by municipalities and
governorates. During last ten years, other establishments are emerging under the auspices of different
ministries to deal with documentation and conservation studies of historic districts, particularly,
Historic and Islamic Cairo project, among others. The Ministry of Planning, the Ministry of
Communications, Information and Technology (MCIT), and even the Information and Decision
Support Center (IDSC) are involved.
5.4.1.4 Italy
In the past years, after the occurrence of a seismic event, a series of legislative actions useful for the
clearing of the emergency and for the reconstruction works has been carried out in Italy. The used
policy strategies were not the same for every earthquake, because of both the differences of situations
and the absence of a comprehensive system of rules to be applied in a seismic emergency. A collection
of the policy strategies adopted in the past can be useful to try to define an unique strategy for seismic
protection.
In order to thread a path among the policy strategies undertaken in Italy in the past, three major
earthquakes occurred in the second half of 20th century have been considered. The referred earthquakes
are the following:
• Friuli, 6th May 1976;
• Irpinia, 23rd November 1980;
• Umbria-Marche, 26th September 1997.
The choice of these earthquakes makes it possible to understand the post-seismic approach in Northern
(Friuli), Central (Umbria-Marche) and Southern (Irpinia) Italy.
For each seismic event a synoptic table is provided. Such tables present, in a chronological order, the
main policy measures undertaken. For each measure, the competent Authority and the main tasks
and/or contents are also indicated.
34
TABLE 5.4. Friuli earthquake, 6th May 1976
DATE
10/05/1976
AUTHORITY
Friuli – Venezia
Giulia Region
MEASURE
Regional Law no.15
18/05/1976
and
20/05/1976
Government
and
Friuli – Venezia
Giulia Region
Parliament
D.P.C.M.
and
D.P.G.R.
Friuli – Venezia
Giulia Region
Friuli – Venezia
Giulia Region
Government
Regional Law no. 17
29/05/1976
07/06/1976
1976
30/10/1976
08/09/1976
19/11/1976
27/04/1977
1977
20/06/1977
Government
Parliament
Friuli – Venezia
Giulia Region
Law no. 336
Regional Law no. 28
Law no. 730
D.P.C.M.
Law no. 30
Regional Law no. 30
08/08/1977
Parliament
Law no. 546
1982
01/12/1986
Parliament
Parliament
Law no. 828
Law no. 879
MAIN TASKS / CONTENTS
-Establishment of a solidarity fund for the intervention after
1976 earthquake;
-Ordering for the demarcation of the damaged areas (after the
first series of seismic shocks, occurred in May).
-Demarcation of the damaged areas (after the first series of
seismic shocks, occurred in May).
-Ordering for the demarcation of the damaged areas (after the
first series of seismic shocks, occurred in May);
-Allocation, on the whole, of 2118 million Euro, for the
emergency (310 million Euro, before the demarcation of the
damaged areas; 1808 million Euro, after the completion of
the demarcation), by considering specific criteria for
industry, commerce, craft, tourism, agriculture, public works
and housing.
-Benefits for small structural repairs.
-Recovery of productive activities (with consequent
allocation of 23.6 million Euro).
-Ordering for further demarcation of the damaged areas
(after the series of seismic shocks occurred in September).
-Further demarcation of the damaged areas (after the series
of seismic shocks occurred in September).
-Allocation, on the whole, of 1782 million Euro.
-Recommendations for structural repair of masonry
structures;
-Intervention on minor cultural heritage (with consequent
allocation of 274 million Euro).
-Further economical contribution for reconstruction, socialeconomical development, cultural heritage safeguard;
-The rules for the realization of the previously mentioned
tasks are defined by Friuli-Venezia Giulia Region.
-Allocation, on the whole, of 904 million Euro.
-Grant aid for buildings interested by state of seismic
readiness;
-Allocation, on the whole, of 607 million Euro.
35
TABLE 5.5. Irpinia earthquake, 23rd November 1980
DATE
24/11/1980
AUTHORITY
Government
1980
Parliament
December
’80
December
’80
Government
MEASURE
D.P.C.M.:
-Declaration of the state
of particularly deep
natural calamity;
-Establishment of the
Extraordinary
Commissioner of the
Government
for
the
Campania and Basilicata
Regions
Law no. 874
-
Extraordinary
Commissioner
Order: Delegation to the
Public
Works
Authorities,
which
delegate the Cities
December
’80
Government
Delegation to the Budget
Ministry,
which
delegates the CNR
January
’81
1981
Extraordinary
Commissioner
Parliament
22/05/1981
and
13/11/1981
14/10/1981
Government
30/03/1990
Interdepartmental
Committee for
the Economical
Planning
Government
Order n. 80
Law no. 219
MAIN TASKS / CONTENTS
(ex art. 5 L 996, 8/12/1980; D.L. 776, 26/11/1980)
-The Commissioner coordinates the assistance and realizes
the emergency services, he provides for aid and assistance,
creating operative centres, temporary lodgings, field
military hospitals
-Confirmation to the Extraordinary Commissioner of the
powers (given to him by the Government) to lead towards
the crossing of the emergency state (with the exception of
the reconstruction plans);
-Establishment of a fund for pressing needs of the
earthquake-stricken people;
-Grant aid for the reparation of the housing;
-Norms of fiscal facilitation and extensions;
-Detection of 2 tasks for the Government: 1) together with
earthquake-stricken Regions and Local Administrations,
damage assessment, within 6 months, in order to take
legislative measures for the reconstruction; 2) by Ministry
of Public Works, together with Superior Council of Public
Works and C.N.R., seismic reclassification of the
earthquake-stricken towns (already stated by Law no.
64/74)
-First temporary demarcation of the damaged areas
-Coordination of the damage assessment, which is based on
forms relating to single buildings, making an essentially
“qualitative” evaluation.
This kind of study was performed for provincial capitals.
-Coordination of the damage assessment, which is based of
forms similar to those used after 1977 Friuli earthquake,
making an analytical evaluation.
This kind of study was performed for the other cities (only
for housing)
-Reorganization of the local scopes for the reconstruction
-System to provide organic reconstruction works and the
economical development of the earthquake-stricken people
(for instance, facilitations for agricultural activities, repair
and reconstruction of industrial settlements, etc.).
-The local authorities provides for housing reconstruction
and to local public works.
-The State provides for the facilities and the economic
development plan for the earthquake-stricken people.
-Demarcation of the damaged areas
D.P.C.M.
Establishment
of
the
C.R.E.D. (Centre of Data
Collection and Elaboration)
-Drafting of annual reports about reconstruction.
Order in Council BE no.
76: Unified code of the
l
f i
i
i
-Reorganization of the series of laws issued after 1981
relating to the post-seismic intervention.
36
laws for intervention in
earthquake-stricken
Campania,
Basilicata,
Puglia
and
Calabria
Regions.
TABLE 5.6. Umbria-Marche earthquake, 26th September 1997
DATE
27/09/1997
AUTHORITY
Government
28/09/1997
Ministry of the
Interior
(delegated for
civil defence by
D.P.C.M.
24/05/1996)
30/03/1998
Parliament
MEASURE
D.P.C.M.:
-Declaration of the state
of emergency
Order no.2668:
-The
Presidents
of
Umbria and Marche
Regions are nominated
Delegated
Commissioners
Law no. 61
MAIN TASKS / CONTENTS
-
-Communication, within 7 days, of the list of towns situated
within the heavily damaged area;
-Implementation of the interventions for private and public
safety;
-Restarting of the ordinary life conditions
-Realization of a plan for emergency measures (together
with G.N.D.T)
-Establishment of a fund for damaged subjects
-Norms for fiscal facilitation
-Planning of urban interventions;
-The damaged Cities must prepare their “Recovery
Programs” (to be carried by the Regions) useful for:
-Reconstruction / recovery with seismic
improvement of destroyed / damaged buildings (by picking
out the damages; summarizing the proposed measures;
calculating the costs; choosing the actuator subjects)
-Demarcation of the damaged areas;
-Financing for the re-establishment of productive
activities
-Grant aid for preventive interventions for reduction of
urban seismic vulnerability (through the so called Unitary
Interventions, referred to entire buildings or to building
complexes)
-Interventions against hydrogeological instability conditions
The funds for reconstruction allocated as a consequence of the series of mentioned post-seismic policy
measures have been subdivided between the different involved subjects, according to their particular
scope.
All the subjects involved in the post-seismic activities are listed in the following. The specific scopes
of each subject are reported.
• Extraordinary Commissioner, for the implementation of the emergency interventions;
• Heavily Damaged Cities, for the grant aid to private citizens to realize the reconstruction, for
the realization of cheap housing, for the realization of local public works ;
• Naples, for the realization of the extraordinary plan for the metropolitan area of Naples;
• Campania and Basilicata Regions, for the reconstruction and repairing in the agricultural,
tourist, craft and entertainment fields;
• Ministry of: Agriculture, Cultural heritage and environmental conservation, Defence,
Finance, Justice, Public works, Postal and telecommunications, Education and Transport,
for reconstruction, repairing and improving of the public works within their references;
• Special Office for Industrial Development, for grant aid to the companies etc.
37
The following diagram shows the subdivision of the total fund (22.850 million Euro) between the
mentioned subjects.
5% 4%
11%
35%
Cities
Neaples
Industrial Development
Extraordinary Commissioner
16%
Ministries
Regions
29%
In the following some data referring to the Unitary Interventions are presented, in order to show the
“answer” given by the Cities to the innovative tools introduced by law no. 61/98.
• Total settlement number:
95
• Total number of Unitary Interventions present in the Recovery Programs:
458
• Total number of buildings listed in Unitary Interventions:
1539
• Average number of buildings for each Unitary Interventions:
3,36
• Number of buildings in U.I. out of the total number of damaged buildings:
35,96 %
• Cost for U.I. buildings repairing:
249 million Euro
• Percentage of the U.I. buildings repairing costs on the total cost for buildings repairing: 37,87 %
5.4.1.4 Maroc
Decree n°2-02-177 dated 9Hija 1422 (22February 2002) approving the Paraseismic Construction
Code, with the acronym referred to by “R.P.S2000”, applicable to the buildings and establishing the
paraseismic regulation and the creation of the National Committee of the Paraseismic Engineering
THE PRIME MINISTER DECREE
HEADLINE I
The Parasismique Construction Code
ART. 1: - approved as was annexed to the original version of this decree, the Paraseismic
Construction Code, abbreviated as "R.P.S.2000", is intended to enforce the paraseismic construction
regulation to insure the building safety.
ART.2- For the application of paraseismic Construction code, R.P.S.2000, to the buildings:
1- the territory is divided into different seismic zones according to their degree of seismic
activitiy,
2- buildings are assigned to different classes according to the degree of protection they must
satisfy. The repartition of seismic zones in districts and communities is fixed by joint decree
emanating from the government authorities in charge of the housing, urban planning, infrastructures
and interior affaires. Before issuing the decree, the opinion of the National Committee of the
Paraseismic Engineering must be considered in accord with the articles 4 and 5 hereafter.
- The classification of buildings is pronounced by a joint decree of the aforesaid authorities
mentioned. The modification of the so-called classification is also made public under the
forms and conditions referred to above.
- The buildings designed according to traditional local techniques and the bearing structure of
which utilizes primarily the ground, straw, wood, palm trees, reeds or similar materials.
38
- The one storey buildings aimed at dwelling or professional uses, with a total area equal or less
than 50 m².
HEADLINE II
The National Committee of the Paraseismic Engineering
ART.4 : A committee was set up under the name of "National Committee of the Paraseismic
Engineering" whose tasks are:
- to propose and issue its opinions with respect to the classification and seismic zoning as well as their
eventual modification per district, as envisaged in article 2 of the code.
- to examine the modifications and to propose improvements to RPS 2000, taking into account,
ART. 5:
This committee is composed, under the presidency of the authority responsible for the
Housing policy, of the representatives of the governmental authorities hereafter:
governmental authority in charge of Urbanism,
governmental authority in charge of interior affaires,
governmental authority in charge of infrastructures,
governmental authority in charge of Mine Exploration and Management,
governmental authority in charge of Scientific Research,
the representatives of the university departments, of the scientific and technical institutes,
the schools of higher education and of professional organizations, the list of which is
ratified by a decree of the governmental authority in charge of the Housing responsibility.
the secretariat of the National Committee of the Paraseismic Engineering is ensured by
the authority in charge of the Housing Policy.
HEADLINE III
Various Provisions
ART.6:
- is declared null the decree n° 2.60.893 of the Rajeb 3, 1380 (December 21, 1960) enforcing the
application of some paraseismic provisions to the Agadir urban perimeter and to the small island of
management belonging to the south-eastern part of the peripheral zone of the city of Agadir.
ART.7: - the Minister in charge of Urbanism, Housing and Environment, the Minister of the Interior
and the Minister of Infrastructures are charged, each one in his field of responsibility, of the execution
of this Decree which will come into effect six (6) months after its publication in the Official Bulletin.
Issued in Rabat on Hija 20, 1422 (February 22, 2002)
The PRIME MINISTER
5.4.1.5 Romania
The Ministry of Transport, Construction and Tourism (MTCT) is in charge with the National Program
for Reduction of Seismic Risk in Romania. MTCT has the responsibility for contracting and financing
standard building laws and technical regulations for earthquake resistant constructions in Romania. It
also represents the National authority for approval of building codes and other technical
regulation/norms for constructions.
The present (2005) organization of the MTCT has a Minister Delegate for Public Works and
Territorial Planning and a Technical Direction for Regulations/Norms for Constructions coordinating
seismic risk reduction policy in Romania.
39
Technical activities related to seismic safety of existing and new important buildings are in the
responsibility of the Technical Commission for Seismic Risk Reduction established at MTCT by
Decision of the Minister.
Important documents related to the management and national policies of reduction of seismic risk in
Romania are:
(i) Governmental Ordinance No.20/1994 concerning measures for seismic risk reduction of
existing buildings, revised 1999; published in Official Gazette of Romania
No.36/29.01.1999 (Ordinance) and No.516bis/25.10.1999 (Methodology for Ordinance
application);
(ii) Order No.6173/NN/1997 of the Minister of Public Works claiming to Municipalities to
prepare: (i) the classification of existing building stock with respect to period of
construction, structure type, class of seismic risk (I-IV) and (ii) the priorities for building
identification and retrofitting.
(iii) Governmental Ordinance No. 578/1998 on the Program of actions of seismic risk
reduction for buildings expertised as having seismic risk class I and for financing the
retrofitting works for tall RC buildings (ground-floor plus more than 4 storeys) built before
1940 in Bucharest.
(iv) A new Government Ordinance in 2001,stated that the Government will 100% advance the
necessary payment, for strengthening of the buildings, to the private owners of apartments
classified as in “seismic risk class 1” buildings (more than 95%of housing units are private
in Romania!). If the owner salary is less than national average, he have to pay back (to the
state) nothing. If it is not, he has to pay the money back in 25 years, with 5% interest.
Anyway, the owner has to agree on the strengthening of its apartment, since he has to leave the
housing unit during the construction work. Of course, the owners do not like leaving and the necessity
buildings for temporary housing during strengthening are not yet implemented. Moreover, if one
apartment owner does not agree on strengthening of its apartment, the strengthening of the whole
building cannot start.
During the last years, the Municipality of Bucharest prepared several thousands of detailed engineering
reports for buildings having significant cumulative seismic damage and high risk of collapse in case of
a strong earthquake (comparable to 1977 event). However, the total number of vulnerable buildings in
Bucharest is probably two times larger than the present number of identified as severely damaged
buildings. In May 2005, from the list of 123 tall residential buildings in Bucharest:
- 5 buildings are fully retrofitted;
- 10 buildings are under retrofitting works;
- 14 buildings have to participate at the bid for construction works;
- 16 buildings have to participate at the bid for design of retrofitting intervention.
The joint effort of the engineers, authorities and building owners for building strengthening in
Bucharest is justified by the certitude that for a 50 –100 years recurrence interval Romanian subcrustal
earthquake, several dozens of pre-war tall RC buildings in Bucharest will collapse(about 60-100
pers/bldg!). Unfortunately, in Bucharest, there are still more than 50 residential buildings built in the
60’ which were identified in seismic risk class 1 buildings.
Bucharest is recognized by the World Bank reports as well as by professionals as the most seismically
dangerous capital of Europe due to the combination of (i) fragile tall RC buildings built before WWII
and (ii) long predominant period of ground vibration during strong subcrustal Romanian earthquakes.
40
The list of cultural heritage buildings in Bucharest prepared by National Institute of Historical
Monuments Bucharest, 2004, contains:
- 87 churches, half of them built in the XVIIIth century;
- 27 palaces, 20 schools, 15 hotels, 23 malls and shops, half of them built in the XIXth century;
- other buildings.
The present state of the retrofitting works for the most
Bucharest are as follows:
Multistory steel structures
Ministry of Transport and
Constructions Palace
Telephone Palace
Multistory reinforced
Government Palace
concrete structures
City Hall Sector 1
Athene Palace hotel
Ambasador hotel
La Fayette Mall
Masonry and reinforced
Palace of Justice
concrete buildings:
Royal Palace i.e.
National Museum of Art
important historical palaces and hotels in
to be retrofitted within WB project
Retrofitted by Romtelecom
to be retrofitted
to be retrofitted within WB project
Retrofitted
to be retrofitted
to be retrofitted
under retrofitting
partially retrofitted
In the case of seismic upgrading of cultural heritage buildings, the Government has decided that the
central role of the state has to be replaced by new partnership models with private sector, international
donors, organized community groups and civil society at large.
The Ministry of Culture has initiated an examination of the state role in parallel with a search for
international assistance and private sector partnerships in order to build financing for the nation's
patrimony. The current Government goal is to seek finance for the sector, using it for improved longterm national cultural heritage partnership and mobilize additional financing from other international
donors such as the World Monuments Fund, UNESCO, Council of Europe, bilateral donors and others.
One major issue is the deterioration and/or loss of a number of historic sites and cultural assets and the
lack of financial resources to prevent further deterioration. A closely related issue is the lack of local
capacity to manage, in a cost effective and sustainable manner the cultural legacy at a time of
transition from state control.
For seismic upgrading/strengthening of historical building in terms of priority of intervention, seismic
risk matrix similar to that used for the general building stock should be implemented, TABLE 5.6.
TABLE 5.6 Priorities for buildings retrofitting
Building importance & exposure (value) class
Seismic
vulnerability
/fragility
class
Essential facilities
1
2
I
II
III
Buildings
that
represent
substantial hazard to human life
in the case of collapse2)
All buildings except
those listed at I and II
Highest priority for retrofitting
Highest priority for retrofitting
Priority for retrofitting
Priority for Retrofitting
Retrofitting
-
1)
1)
Hospitals and facilities having emergency treatment facilities, Fire, rescue and Police stations, Communications centers, Buildings and others structures
having critical national defence functions;
2)
Schools with capacity greater than 250, buildings with capacity greater than several hundreds of persons, health care facilities with capacity of 50 or
more resident patients but not having surgery facilities.
41
Proposed risk matrices for prioritisation of intervention on cultural heritage buildings, TABLE 5.7.
Seismic
vulnerability/
fragility class
i
ii
iii
TABLE 5.7. Seismic risk matrix
Combined class: Importance & value
I
II
III
IV
1
1
3
3
1
2
2
3
3
March 4, 1977: Collapse of the two fragile high-rise RC buildings built before 1940 in the Center of
Bucharest
5.4.1.6 Slovenia
Regarding the intervention strategies at the moment in Slovenia there is no corresponding legislative
available. In practice, a technical commission of experts, established by the government, estimates the
damage and gives the recommendations for the buildings retrofitting. The repair is financed partly by
the state and partly by the owners. The technical commission decisions are based mostly on the
following codes (and past experience):
• Technical regulations for repair, strengthening and reconstruction of buildings damaged in
earthquakes, Slovenia (Yugoslavia), 1985.
• Eurocode ENV 8-1-4: Strengthening and repair of buildings.
5.4.1.7 Turkey
The Ministry of Reconstruction and Settlement, the predecessor organisation of the current Ministry of
Public Works and Settlements, was established in 1958 to reduce the risk of death and injury to the
population, and to reduce the scale of the economic risks involved from earthquake and other natural
disasters. The single and most important mandate was to implement two laws, the so-called
“Development Law” and “Disaster Law,” which were created by the Ministry of Reconstruction and
Settlement in 1959.
42
The current Development Law (No.3194, termed the “Reconstruction Act” as literally translated from
Turkish) was enacted in 1985, and it is the fourth generation in a tradition of such legislation in
Turkey.
The Development Law is the principal legal instrument governing how buildings are constructed. This
law was devised to ensure the establishment of settlement areas and structures in compliance with
planning, health and environmental conditions. This law has a few articles in Part 4 that regulate the
supervision of building construction. The law holds municipalities (or governorates for buildings
outside of urban areas) responsible for design supervision. Construction supervision is entrusted to the
inspector, so-called “engineers of record.” For certain classes of buildings to be built in nonmunicipality areas, non-engineering degree holders have also been enabled to serve in this capacity.
There are other exceptions granted for rural settlements. Plans for areas remaining inside or located
outside of municipal and residential areas, and all structures to be constructed are subject to provisions
of this law.
In Turkey, the legal system functions by chartering by-laws, regulations, or statutes that regulate how a
given law is enforced. Numerous regulations complement the Development Law as follows:
- Standard building regulations for non-metropolitan municipalities
- Land and property sharing with renewed alignments according to Article 18
- Standards and procedures for preparing and revising plans
- Building regulations for areas without a plan
Illegal Housing Construction Laws
In Turkey, the informal settlement sector plays an important role in housing construction. Illegal
housing, or so-called “gecekondu”, a Turkish word meaning “overnight construction”, began to appear
in the 1940’s. At first, the government tried to remove gecekondu. However, rapid increase of
gecekondu and massive political power of its inhabitants forced the governmental policy to take more
feasible measures (Hirayama, 2001; Kobayashi et al., 2001).
In 1953, a law was issued to prohibit new gecekondu but permit existing illegal housing. In the late
1950’s, construction of illegal housing became industrialized. Planned but illegal housing
development, and its selling and renting were established as a commercialized system.
In 1963, the Republic’s five-year national development plan was institutionalized, and housing
provision was included under the plan.
In 1966, a major shift in the housing policy was made when a gecekondu law was issued. The law
designated gecekondu areas that satisfied certain conditions as “improvement areas,” and their
improvement and infrastructure were promoted. Gecekondu areas that did not satisfy certain
conditions were designated as “prohibited areas,” and the removal of housing from these areas along
with provisions of alternative housing were promoted. Illegal occupants in public areas were requested
to buy the land in short period of time as sub-division, and then they become subject to property
taxation. Gained revenue was to be used for the improvement of the gecekondu areas.
In Istanbul in the 1950’s, the informal sector consisted of 45% of its housing construction. In the
1970’s, the informal sector accounted for over two thirds of housing construction. Gecekondu law was
revised later in 1976 and in 1983, maintaining basic principles from its first version.
In 1985, financial assistance systems for acquisition of housing such as the Mass Housing Law, and
the Mass Housing Fund were outlined under the 5th National Development Plan. In the same year, a
43
new reconstruction law penalized illegal development covering areas over 1000 m2, but small illegal
housing developments covering areas less than 1000 m2 were legalized.
Recent Decrees related to Safe Construction
Following two earthquakes in 1999, new decrees were developed to ensure safe construction (Gulkan,
2001).
a. Building Construction Supervision (Decree No. 595, April 10, 2000)
Decree No. 595 was issued to ensure that nominal quality standards are abided within the building
construction continuum. Institutional buildings are excluded. The individuals deemed responsible for a
given building are the design engineer, contractor, site engineer and building supervision firm. Design
engineers are required to have the title of “expert engineer,” similar to a professional engineer. In
essence, the building supervision firm exercises the duties of the municipal or governor offices in
ensuring both the correctness of the designs and conformance of the actual construction to the design.
In each provincial capital and town with populations numbering more than 50,000 inhabitants, a
building supervision oversight commission is established under the general coordination of the field
office of the Ministry of Public Works and Settlements. Ankara’s “Building Supervision Supreme
Council” is embedded in the same ministry and manages this hierarchical structure.
Fees for design and construction supervision range from 4 to 8 percent of the estimated cost of the
building and are disbursed by the owner through the municipality. Unless there exists a confirmation
that the building has been completed in conformance with the actual design, municipalities are not able
to grant occupation permits for people to move into the premises.
The building construction supervision firm is the party primarily responsible for offsetting any losses
incurred by the owner that may arise during the first ten years after the occupation permit is issued,
including those caused by natural disasters. To ensure this compensatory liability, firms must purchase
insurance for each job they supervise. All firms engaged in this type of activity have this coverage.
The enforcement of this decree was initiated in 27 pilot provinces, including all that were impacted by
the 1999 earthquakes. An omission in the text of the decree is the detailed construction inspection
procedures that are required for effective quality assurance. Architects have been left out of the
inspection procedures, with the civil engineering profession having received prime responsibility there.
A number of regulations have also been issued to facilitate the implementation of the decree.
b. Regulation for Implementation of Construction Supervision (May 26, 2000)
Construction supervision firms are classified into three groups in order of reduced responsibility and
manpower requirements. These firms must be owned by a majority of engineers or architects. Their
chief mission is to ensure that the designs conform to the appropriate building code as well as the
seismic code. Local site evaluations are specifically mentioned because of past experiences with
liquefaction and loss of soil strength. This regulation also contains clarifications regarding the manner
in which different-level supervision councils are to function, and how their records are to be kept.
c. Revision of the Law on Engineering and Architecture No. 3458 and Law on the Union of
Chambers of Turkish Engineers and Architects No. 6235 (Decree No. 601, June 28, 2000)
The practice of engineering and architecture, and the empowerment of engineers and architects to
organize themselves into chambers and a union comprising the different chambers are regulated by
these two laws. With the introduction of “expert” engineers or architects in the process of construction
supervision, corresponding amendments to the parent laws were required. This decree achieves that
44
objective. The chambers are enabled to set the guidelines for conferral of the expert title, but generous
transition (grandfather) clauses have also been admitted. General Conditions for Mandatory Financial
Liability Insurance for Construction Supervision Firms (July 10, 2000). This directive issued by the
Under secretariat of the Treasury sets the rules and procedures for the purchase of the mandatory
financial liability insurance all supervision firms must have for each construction they undertake to
oversee. Coverage articles refer to “unreasonable” damages caused by the disaster as being excluded
from the intent of the underwriting, but no specific guidelines are mentioned.
In successive articles, the obligations of the insurer and the insured are spelled out when events leading
to physical damages have occurred because causes of damage are often not easily ascribed to only one
party in the building delivery process. The insurance premium is 1.3 percent of the insured value.
d. Testing Laboratory Requirements for Decree No. 595 (July 30, 2000)
Independent testing laboratories must certify that minimum requirements are met for building
materials used in construction. This directive and a companion set out the requirements for these
laboratories.
Disaster Laws
The 1982 Constitution
The 1982 Constitution outlines the rules and procedures for the declaration of a state of emergency and
the suspension of fundamental rights.
Article 15 describes the suspension of the “Exercise of Fundamental Rights and Freedoms” as follows:
“In times of war, mobilization, martial law, or state of emergency, the exercise of fundamental rights
and freedoms can be partially or entirely suspended, or measures may be taken, to the extent required
by the exigencies of the situation, which derogate the guarantees embodied in the Constitution,
provided that obligations under international law are not violated.”
Article 119, "Declaration of a State of Emergency on Account of Natural Disaster or Serious
Economic Crisis," in the constitution defines the activation of a state of emergency. The article states
that "in the event of natural disaster, dangerous epidemic diseases or a serious economic crisis, the
Council of Ministers, meeting under the chairmanship of the President of the Republic may declare a
state of emergency in one or more regions or throughout the country for a period not exceeding six
months."
Article 121 states the "Rules Relating to the State of Emergency" as follows: "In the event of a
declaration of a state of emergency under the provisions of Articles 119 and 120 of the Constitution,
this decision shall be published in the Official Gazette and shall be submitted immediately to the
Turkish Grand National Assembly for approval. If the Turkish Grand National Assembly is in recess,
it shall be assembled immediately. The assembly may alter the duration of the state of emergency,
extend the period, for a maximum of four months only, each time at the request of the Council of
Ministers, or may lift the state of emergency.
The financial, material and labor obligations which are to be imposed on citizens in the event of the
declaration of state of emergency under Article 119 and, applicable according to the nature of each
kind of state of emergency, the procedure as to how fundamental rights and freedoms shall be
restricted or suspended in line with the principles of Article 15, how and by what means the measures
necessitated by the situation shall be taken, what sort of powers shall be conferred on public servants,
45
what kind of changes shall be made in the status of officials, and the procedure governing emergency
rule, shall be regulated by the Law on State of Emergency.
During the state of emergency, the Council of Ministers meeting under the chairmanship of the
President of the Republic, may issue decrees having the force of law on matters necessitated by the
state of emergency. These decrees shall be published in the Official Gazette, and shall be submitted to
the Turkish Grand National Assembly on the same day for approval; the time limit and procedure for
their approval by the assembly shall be indicated in the Rules of Procedure."
National Development Plan
Unlike former plans, the 8th National Development Plan fully addresses natural disasters in section
seven, “Natural Disasters,” and in chapter nine, “Enhancement of Efficiency in Public Services.”
The plan describes objectives and principles as follows: “The main objective is to establish the social,
legal, institutional and technical structure for reducing the damages of disaster to the minimum through
measures to be taken. Central coordination in the establishment of this structure is the main principle.
Through continuous and systematic training efforts, measures shall be taken against earthquakes and
other disasters, and it shall be ensured that these disasters shall be perceived as common natural events.
Training efforts for people shall be continued to include the social ethical rules.
Necessary efforts shall be made to guarantee sufficient security for all the existing or future infra and
superstructures. A small part of the large resources, which were utilized after the disasters but proved
not to be efficient, shall be utilized under a plan before the disaster to take measures for reducing the
damages of a possible disaster.
Since design of the disaster-proof buildings requires specialization, emphasis shall be given to
earthquakes and other issues on disasters in engineering graduate programs. Furthermore, programs
improving the sense of responsibility of the engineers and laying down a professional ethic shall be
emphasized. Earthquake engineering postgraduate programs shall be introduced by the technically
eligible universities and existing programs shall be improved. Efforts shall be made to reduce
deficiencies of engineering in practice.
Since most of the building stock is not secure against earthquakes, these buildings shall be examined
and strengthened systematically against earthquakes, starting, first of all, from the places where
earthquake occurrence possibility is high.
Establishment of Building Assessment Centers where competent engineers shall work for assessment
and strengthening of the existing buildings against earthquakes shall be supported.
With a view to making the principles and methods of the field use and construction plans sensitive
against disasters, related legislation shall be reviewed and effective mechanisms shall be introduced for
strict implementation. Liabilities and relevant sanctions of those who will act against the rules shall be
revised.
A disaster management system, in harmony with the existing legal and institutional structure and
including the studies for National Extraordinary Situation Plan shall be made. This system shall cover
a fast, effective and comprehensive rescue and first aid operation in order to reduce the damages of the
disasters before and during the disaster and accomplish the functions towards eliminating the
economic, social and psychological damages of the disaster.”
46
The plan describes legal and institutional arrangements as follows: “Necessary arrangements shall be
made in the legislation to make the Turkish Emergency Management Institution operative. The Law on
Engineers and Architectures laying down the duties, authorities and responsibilities of the engineers
and the Law concerning the Turkish Engineers and Architectures Chamber Union setting out the duties
and authorities of the professional chambers shall be revised to introduce a concept of Competent
Engineering.
Construction Law shall be amended to introduce a sound construction control system and revised to
include the liabilities of those acting against the rules and the sanctions to be applied to them.
The Law on Municipalities and the Metropolitan Municipalities Law shall be amended to bring about a
sound construction control system and revised to arrange the duties, authorities and responsibilities of
the local administrations on the determination of natural disaster threats and risks and reduction of
their likely damages.
Full and accurate implementation of the provisions of the Natural Disaster Regulation is considered
adequate for ensuring earthquake-proof building design in the future. Legislation for other disasters
needs to be updated and accurately implemented.
Related provisions of the Civil Code, Law of Obligations and Trade Law shall be reviewed as regards
construction controls, responsibilities and insurances, and necessary legal arrangements shall be made
to this end.
The Law on the Measures and Assistance in Natural Disasters Affecting Life which considers the state
as a natural insurer covering all damages incurred shall be amended to cover only the cases which are
impossible to be insured, thus public liability shall be limited.
A national disaster information system shall be established through which cooperation with institutions
in the other countries and international bodies shall be possible. A national disaster communication
system that would provide continuous service during the disaster shall be established.”
Disaster Law (Law No. 7269)
A “law on the measures to be taken and assistance to be directed due to disaster having influence on
social life,” or so called “Disaster Law,” was issued in 1959 as a fundamental law in dealing with
disasters, and was later amended in 1968.
The main scope of this law is to provide public intervention capacity and to improve the efficiency of
relief operations after disasters such as earthquakes, fires, floods, erosions, rockslides, avalanches, etc.
For this purpose, the law entitles extraordinary powers for provincial and district governors, making
them the sole authority with powers commanding all public, private, and even military resources to
manage response activities. Each governor is responsible for drawing a relief operation plan to become
effective immediately after a disaster. The relevant ministries, provincial administrations, and
subdistricts are required to draw up their own emergency preparedness plans. A disaster fund is
allocated annually from the national budget for all recovery expenses.
Regulations Concerning the Fundamentals of Emergency Aid Organisation and Planning
Associated with Disasters (Decree No. 88-12777)
As one of the by-laws pursuant to Article 4 of the Disaster Law, this regulation was established in
1988 by the Ministry of Public Works and Settlements. The object of these regulations is to define the
formation and duties of emergency aid organizations by effectively planning the facilities and
47
resources of the State before natural disasters occur to ensure that, in case of a natural disaster, the
State gets fastest access to natural disaster areas and survivors get efficient first aid. Provincial and
district governors are entitled with the most responsibility and given extraordinary power to seize men,
vehicles, land, and properties in the event of a disaster.
These regulations stipulate that the Provincial Emergency Aid Committee be formed under the
governor and that the Permanent Provincial Disaster Office be established under the Provincial
Directorates of the Ministry of Public Works and Settlements.
The Provincial Disaster Office is composed of nine service groups and associated subservice groups,
formed by various public organizations. The service groups will work for the victims from the
beginning of the disaster up to 15 days, though the termination date of the services may be extended.
The regulation also stipulates that district governments set up district emergency aid committees
including the district mayor and formed under the district governor, and to form district emergency aid
service groups and provide services which are similar to or reduced in scale to the provincial ones.
Civil Defense Act (No. 7126)
Civil Defense Act (No. 7126) was issued in 1959 and serves as a legal basis of present civil defense.
This act entitles civil defense with rescue work authority. Organizations that operate rescue activities
must have a protocol with civil defense.
Laws Related to Fire Brigade
Services of the fire department and control of hazardous facilities are defined as duties of municipality,
as defined in the Municipality Act, and in Metropolitan Municipality Act. In addition, there are 30
laws, rules and regulations in total that are concerned with fire, though special fire laws do not exist.
Laws Related to Compulsory Earthquake Insurance
Following are a set of decrees related to earthquake insurance that were issued after the 1999 Marmara
Earthquake (Gulkan, 2001):
a. Compulsory Earthquake Insurance (Decree No. 587)
Compulsory earthquake insurance was issued as an act on December 27, 1999. All existing and future
privately owned property is required to contribute to the Turkish Catastrophe Insurance Pool (TCIP).
Non-engineered rural housing and fully commercial buildings are excluded. The intention of this
decree is to create a fund contributed to by homeowners’ annual payments for use in disasters so that
no one will be left homeless, with a nominal sum, currently capped at US$28,000, being disbursed
immediately to homeowners who are left homeless.
An important feature of this decree is its denial of assistance in accordance with the Disasters Law No.
7269 when homeowners have not participated in the TCIP. This article became operational in March
2001. A number of penalty clauses, missing from the original text, have been added when the draft law
was forwarded by the Undersecretariat of the Treasury to parliament.
b. General Conditions for Compulsory Earthquake Insurance (September 8, 2000)
Issued by the Under-secretariat of the Treasury, this directive regulates the manner in which insured
parties shall make claims for losses against the Natural Disasters Insurance Council (“DASK” is the
Turkish abbreviation). The amount payable by DASK essentially covers the minimum amount
required for a modest new accommodation. Homeowners can, of course, purchase additional voluntary
insurance if their property is worth more. However, for additional coverage to be purchased, the
48
compulsory insurance policy must be presented to the insurer. TCIP coverage is for property only and
does not extend to contents or life.
TCIP is insurance, not compensation. This means that payments will be proportional to actual losses,
i.e. an indemnification will occur. TCIP is a policy that specifically covers the earthquake peril.
Damage due to fires, explosions and/or landslides triggered by an earthquake is also automatically
covered. Homeowners may purchase additional voluntary insurance for their property if they so wish.
c. Tariff and Instructions for Compulsory Earthquake Insurance (September 8, 2000)
While, for 2000, the limiting compensation equals 20 billion TL (approximately US$28,000),
premiums are differentiated based on location with respect to the earthquake zone map and on type of
construction. The premium for the highest risk buildings such as non-reinforced masonry is rated at 0.5
percent of the assessed value, which cannot exceed 20 billion TL.
Disaster Management Organization
With the experience of two earthquakes in Turkey in 1999, many disaster management organizations
were established at various levels, from prime ministry to municipality. The following describes the
foundation, organization and function of these organizations:
Central Government
a. Prime Ministry Disaster Crisis Management Centre
The Prime Ministry Crisis Management Centre was established at the time of 1999 Marmara
Earthquake to integrate the disaster response of the government. Later, the General Directorate of
Emergency Management under the Prime Ministry was established as a permanent organization to
ensure efficiency in emergency management.
The activities of the general directorate are as follows:
- To establish emergency management centers within local governments, determine their
principles and carry out inter-institutional coordination
- To carry out preliminary actions, make short- and long-term plans, monitor and evaluate
databases in order to prevent and mitigate disasters
- To coordinate the utilization of public and civilian vehicles and facilities in case of
emergencies
- To promote volunteer efforts by organizations and individuals in emergencies
- To coordinate the procurement, warehousing and distribution of relief materials
b. Ministry of Public Works and Settlements
Motivated by frequent earthquakes in Turkey, the Ministry of Reconstruction and Resettlement was
established in 1958. Its aims were to reduce the risk of death and injury to the population, and to
reduce the scale of the economic risks. The name of the ministry has been changed to the current name
through organizational restructuring.
General Directorate of Disaster Affairs:
In the ministry, the General Directorate of Disaster Affairs is the organization responsible is for
disaster management. In the directorate, the Earthquake Research Department has three subdepartments focusing on earthquake research.
49
- The Earthquake Engineering Department is responsible for providing the necessary measures
for constructing earthquake-resistant structures and for providing and developing basic
principles for the rehabilitation of structures damaged by earthquakes.
- The Seismology Division is responsible for the establishment, operation and development of
the National Seismological Observation Network and for the monitoring of micro seismic
activity to aid in earthquake prediction and to study aftershock activities.
- The Laboratory Division is in charge of carrying out international joint projects and is
responsible for building and updating a GIS, which covers earthquakes and other data for the
whole country. It also sets up and operates the strong motion recording stations covering the
whole country.
Central Disaster Coordination Council:
The Central Disaster Coordination Council is formed in case of a disaster as shown in FIGURE 5.10.
However, since the prime ministry has established a crisis management centre that deals with
administrative aspects, this ministry now mainly deals with technical aspects.
FIGURE 5.10. Organization of the Central Disasters Coordination Council (Oktay, 1999)
c. Civil Defense
The Civil Defense was organized as apart of military in 1928. The current Civil Defense became an
independent organization with the “Civil Defense Act” of 1959. With the experience of major
earthquakes, the Civil Defense has reinforced its rescue teams.
The Civil Defense is unarmed, protective, and involved in the development of rescue measures and
activities. The General Directorate of Civil Defense has been carrying out these services under the
auspices of the Ministry of Interior.
The organization consists of both central and provincial bodies. The central organization includes the
General Directorate, Civil Defense College, and the Warning and Alarm Centers. Provincial
organizations have been set up as Province and Town Civil Defense Directorates, Civil Defense Local
Forces, and Civil Defense Search and Rescue Units Directorates. In addition, every governmental
organization must have a civil defense section, for firefighting, rescue, first aid, and the security of
50
each organization. The head of the civil defense section in each organization is appointed by the
central government. The goal and purpose of the Civil Defense Organization is to minimize life loss
and other types of losses during warfare or any natural disaster.
d. Turkish Red Crescent
The International Federation of Red Cross and Red Crescent Societies was founded in 1919, and it
comprises 176 members (making up the world's largest humanitarian organization). The international
federation provides assistance without discrimination as to nationality, race, religious beliefs, class or
political opinions.
The federation's mission is to improve the lives of vulnerable people by mobilizing the power of humanity.
Vulnerable people are those who are at greatest risk from situations that threaten their survival, or their
capacity to live with an acceptable level of social and economic security and human dignity.
The federation carries out relief operations to assist victims of disasters, and combines this with
development work to strengthen the capacities of its member National Societies. The federation's work
focuses on four core areas: promoting humanitarian values, disaster response, disaster preparedness,
and health and community care.
The Turkish Red Crescent has a fund source independent of the government. Planning of the Turkish
Red Crescent is centralized under the Ankara Planning Directorate, which plans the distribution of
food and tents. There are 600 branches in Turkey covering every province. The Turkish Red Crescent
Society’s services are relief services, youth services, blood services and health services.
e. Natural Disasters Insurance Council
As earthquake insurance became obligatory for building owners in urban areas on March 27, 2001,
management of the insurance pool is entrusted to a new entity called the “Natural Disasters Insurance
Council” (DASK), under the General Directorate of Insurance in the Ministry of the Treasury.
(2) Provincial Government
Provincial Rescue and Relief Committee:
On February 1999, before the Marmara Earthquake, the Istanbul Governorship had established a
provincial disaster relief committee and execution groups, according to regulation, as shown in
FIGURE 5.11. The committee is the decision-making body chaired by the governor. Nine provincial
emergency service groups were formed for the execution of emergency response efforts in different
categories of service.
Governorship Disaster Management Centre (AYM):
The Istanbul provincial governorship established the Disaster Management Centre (AYM in Turkish
abbreviation) as the organization for integrated disaster management, by the order of president just
after the 1999 Marmara Earthquake. The Disaster Management Centre consists of the council, the
scientific consultancy committee, the administrative board, and the management office as shown in
FIGURE 5.12.
Under normal conditions, it aims to promote and coordinate disaster preparedness of concerned
organizations, and it will be shifted to the Provincial Disaster Management Centre in case of crises. In
addition, in case of a major disaster that affecting several provinces, a Regional Disaster Management
Centre is established under the MPWH.
51
FIGURE 5.11. Organization of the Provincial Rescue and Relief Committee (Oktay, 1999)
FIGURE 5.12. Organisation of Governorship Disaster Management Centre
52
(3) Metropolitan Municipality Government
Istanbul Metropolitan Municipality Disaster Coordination Centre (AKOM in Turkish abbreviation)
was established in 2000 due to the necessity to establish a communication channel within IBB, by the
order from mayor and authorization by the Municipal Assembly. The initial members of the centre
were the fire department, health department, ISKI and IGDAS. Planning, mapping, and other
departments joined later on to form the current organization.
The object of AKOM is to coordinate tasks among organizations within Istanbul Metropolitan
Municipality. The organization structure of AKOM is shown in FIGURE 5.13.
FIGURE 5.13.Organization of Disaster Coordination Centre in IMM
(4) District Disaster Management Centre
The district disaster regulation requires establishing a permanent district disaster management centre in
every district, with the district head serving as the head of the centre. Mayors in each municipality will
work with district heads under the governorship.
Each disaster management centre is connected to AYM, but it does not have a direct relationship with
AKOM. ISKI and IGDAS have subsidiary offices in each district, and they are designated to work
with each district management centre. The real situations of the district disaster management centers
vary from district to district. In some municipalities, the municipalities have built their own disaster
management centre, and it provides office space for a district head. In this way, the municipality
disaster management centre practically works as a district disaster management centre. In other
municipalities, existing buildings are used as a district disaster management centre, and district head
and related service group organization are included.
53
5.4.2 Building Codes and Codes Inter-Benchmark Periods
5.4.2.1 Algeria
The Algerian seismic regulation has gone through several stages, depending on the different seismic
events that have marked the seismic activity of the north of Algeria. Indeed, already in 1716,
following the seism which devastated Algiers and made approximately 20000 victims, then Dey of
Algiers promulgated an edict under the term of which he prescribed constructive recommendations.
Among these recommendations, the arching system, with its flexibility, was found to absorb lateral
forces without damages and transmitting them to the floors. Floors were made in wooden joists fixed
to the walls or supported on wooden beams.
Following the earthquake of Orléanville in 1954 (later on El Asnam and then Chlef after the 1980
earthquake), the French colonial authorities at that period edited and published the AS55, which
became, after various corrections and updating, the PS69 (1969).
The first draft of the Algerian seismic regulations was started in 1976 in collaboration with the
University of Stanford (USA). Stanford University was more precisely charged of studying the seismic
risk in Algeria in the aim of providing a chart for the seismic risk on the basis of the seismic history of
the country. This study was finished in 1978 and has been used for the development of the first
Algerian seismic regulations code published in 1981 after the fatal earthquake of 1980 which
devastated the region of Chlef. It is to be noted that the relatively rapid publication of the Code (in
1981) after the earthquake obeyed to the recommendations that were made after the disastrous event.
FIGURE 5.14. History of Algerian seismic regulations
As can be seen from the chart, the Algerian seismic design regulations have been updated after each
earthquake that has caused damages and losses of lives.
54
Indeed, it is more about implementation than updating the seismic guidelines that were never fully
respect by the construction industry and the supervising bodies were never strict enough.
The 2003 earthquake showed it very clearly that where the RPA guidelines were respected, buildings
did not collapse and lives were saved even though in the previous version of the code, the region hit
was considered as a medium risk zone.
5.4.2.2 Egypt
5.4.2.2.1 Development of building codes
The following is a brief summary on development of codes for computing seismic loading and design
of structural elements to resist earthquakes. It is to be noted that – to date – none of these codes
address historical construction:
•
The first seismic loading provisions were published by the Egyptian Society of
Earthquake Engineering 1988. However, due to lack of official backing, it had minimal impact.
•
The first code to include seismic loading was the Egyptian Code for Reinforced
Concrete Construction, 1989 which included an equivalent static method with a minimum
lateral load of 1%.
•
A similar equation was defined in the Egyptian Load for Foundations, 1990, but with
different seismic coefficients.
•
In order to avoid the discrepancy between the two codes, reference to seismic loading in
both codes was superseded by the Egyptian Code for Loads and Forces, 1993. This code
followed UBC 85-type equation for the equivalent static method. It states that dynamic analysis
is required for certain types of buildings. However, it does not provide a response spectrum or
criteria for time history records. The seismic zoning map divided Egypt into three zones,
FIGURE 5.15. The effect of soil was included by dividing the soil into three categories. Based
on the soil type, the factor S was chosen and included in computing the equivalent static force.
The value of S ranged from 1.0 to 1.3, depending on the type of soil. The Code stated that
dynamic analysis is required for certain types of buildings. However, it does not provide a
response spectrum or criteria for time history records.
FIGURE 5.15. Seismic zoning map of the Egyptian Code for Loads and Forces, 1993.
55
•
This why the code for loads has recently been updated (2003). The new code follows a
Euro-code format, and minimizes the use of the equivalent static method. It included a zoning
map that divided Egypt into five zones, and provided peak ground acceleration for each zone
(ranging from 0.1 to 0.25 g), FIGURE 5.16. The effect of soil is taken into consideration in the
new code by dividing the soil into 4 types. The code recognizes two types of response
spectrum, one for the north coastal area (Type 2) and one of the remaining areas of the country
(Type 1). Type 2 has an extended plateau to cater for long-period components. Loads in the
new code vary substantially from the older version, and are generally higher. Soil
characteristics in different localities in Egypt and their impact on seismic wave attenuation and
modification are important parameters that control earthquake risk.
FIGURE 5.16. Seismic zoning map of the Egyptian Code for Loads and Forces, 2003.
5.4.2.2.2 Building stock
The building stock in Egypt may be divided into engineered and non-engineered structures. Nonengineered structures may be either old buildings, such as most buildings in the old Cairo
neighborhoods, as well as historical monuments, or more modern construction, in semi-rural areas.
Construction material often used in these buildings is stone masonry laid in lime mortar. Engineered
structures include a mixture of reinforced concrete skeletal structures (slabs, beams, and columns are
reinforced concrete), concrete slabs poured on top of masonry walls, wooden slabs on top of masonry
walls, prefabricated concrete construction, and adobe construction. A survey of the building stock in
greater Cairo two decades ago indicated the percentage of each construction type as follows:
Type
%
R.C.
skeleton
25.2%
Prefab.
0.3%
R.C. slab
Other slab
36%
22%
Adobe
Other
13.1%
3.4%
The same survey classified the buildings by year of construction as follows:
Date
Before 1940
%
14.2%
1940-59
16.2%
56
1960-79
38.8%
After 1980
30.8%
5.4.2.3 Greece
Laws – Regulations
In 1928, after the destruction of Corinth, the first Code containing seismic provisions for structures
was brought out in Greece. The Code had a local character, as it was valid only for structures in
Corinth and the neighboring town of Loutraki.
In 1959 the first seismic Code for the whole country was published. It was the result of the work of
Prof. A. Roussopoulos, “father” of earthquake engineering in Greece and Europe. According to the
code provisions, horizontal earthquake forces on the structure should be defined as H = εV , where ε
= seismic coefficient and V = sum of vertical loads.
The distribution of earthquake forces along the height of the structure was considered to be uniform.
Static 3Dimensional structural analysis was proposed according to a pioneering for the time being
method, by Prof. Roussopoulos and Japanese scientists. For every floor, the mass center and stiffness
center (under assumption of rigid structure) were determined. The influence of overturning moments
due to distress was not taken into account. The control process was accomplished according to the
theory of allowed stresses, the values of which were increased up to 20%. For Athens, the ε
coefficients were defined as 0.04, 0.06 and 0.08, depending on the soil conditions (rock, medium,
soft). As a consequence, the buildings of the city, whose largest part is built on rock, were analyzed
with seismic coefficient value at 0.04.
In an effort of comparison with current provisions for control of reinforced concrete buildings by the
method of partial safety coefficients, the above mentioned values need re-examination. For reasons of
equivalence, they are multiplied by the global safety factor 1.75 and the partial one 1.15 for steel
reinforcement, and divided by the increasing factor 1.20 of allowed stresses. As a result, the values of
coefficients turn up to be 0.065, 0.10 and 0.13.
After the earthquakes of 1978 and 1981, the two biggest Greek cities Thessaloniki and Athens, faced
the short-term need of revising the existing Code. This was really imperative as knowledge on the field
had progressed and construction types and methods had changed. Assumptions concerning the
stiffness of structures and the negligibility of overturning moments had to be re-assessed. The
challenge of urgent solutions didn’t permit a radical revision and finally in 1984, “supplementary
provisions” on the existing Code were released. They introduced a triangular shaped distribution of
earthquake induced forces along the height of the structure, a more specific 3D structural analysis and
special constructive detailing measures (strong columns-weaker beams, increased steel reinforcement
in junction areas etc.)
In 1995, the New Greek seismic Code was published (NEAK), having much in common with
Eurocode 8. The country is divided in 4 zones with appropriate values of Peak Ground Acceleration
(PGA) defined at 0.12g, 0.16g, 0.24g, 0.35g. Athens is classified in the second zone, meaning
PGA=0.16g. The design spectrum for frame structures can be derived from the elastic spectrum after
applying a behavior factor of maximum value q=4.0. Comparing this design spectrum to the elastic
response spectrum actually produced by the Athens earthquake (1999), a significant difference (of
factor 20) for stiff structures is observed. The difference is also considerable between the elastic
spectra of the Code and of the real earthquake which in the area of small fundamental periods is of
factor 3 ( 0.16 g ⋅ 2.5 = 0.4 g instead of the actual 1.2 g ).
57
On April 2001, the currently used edition of the Greek seismic Code (EAK2000) was released, as a
revision of NEAK after 4 years of implementation. It comprises revisions and completions which were
considered necessary based on experience acquired through NEAK and recent seismic events, as well
as adaptive paragraphs in respect to EC8 and EC7.
As far as ancient and historical buildings before Codes’ existence are concerned, there have been some
relevant legal provisions such as in law 5351-art.52 /1932 on antiquities, law 1469/1950 on
preservation of exceptional structures and artistic achievements after 1830 and law 1337/1983 on
urban planning and evolution. Nowadays, there is an effort in process aiming at covering the existing
gaps on current practice in retrofit methods by creating a National Code for Repair and Strengthening,
at least for common structures. Still, current practice is the result of gathered experience, international
standards and published scientific wok, assisted by national pre-standards and supplemental
publications such as the “Recommendations for pre-seismic and post-seismic interventions in
buildings” by the Greek Earthquake Planning and Protection Organization.
Percentage of Greek buildings after code applied
9%
13%
46%
New codes
"Supplementary" provisions
32%
Without seismic code
Seismic code 1959
FIGURE 5.17. Buildings assignment according to the Greek Technical Chamber
5.4.2.4 Italy
5.4.2.4.1 Current codes’ orientations
According to the Italian seismic legislation (Order of the President of the Council of Ministers 20th
March 2003 no. 3274, Annex 2, Section 11.1), the interventions on existing buildings can be divided
into two groups:
•
Seismic improvement, i.e. the realization of interventions faced to obtain a higher safety
degree;
• Seismic upgrading, i.e. the realization of a series of structural interventions to make the
structure able to withstand the new earthquake design actions
This distinction was introduced for the first time in Italian seismic legislation by the Ministerial Decree
(DM) 24th January 1986.
5.4.2.3.2 Rules referring to existing important buildings
The OPCM 3274/2003 establishes that the owners of:
• buildings of strategic importance and facilities relevant for civil defence,
58
•
buildings and facilities that can be relevant if related to the consequences of their
possible collapse
must check their buildings from the seismic point of view, within 5 years (OPCM 3274/2003, article 2,
paragraph 3), considering a priority for buildings and facilities present in seismic zones 1 and 2.
On the basis of the available financial resources, it must be realized a temporal plan of structural
checks and the individuation of the buildings and facilities previously mentioned. The Department of
Civil Defence (DPC) makes it referring to the works of state reference, while the Regions make it
referring to the works of regional reference (OPCM 3274/2003, article 2, paragraph 3). The Decree
21st October 2003 of the Chief of DPC (Official Journal, 29th October 2003) establishes a list of the
buildings and facilities of state reference and includes the historical buildings among the ones of
relevant importance in case of collapse. The lists of regional reference must be prepared by each
Region.
The financial resources necessary for the mentioned structural checks derive from:
• those deriving from article 80, paragraph 21 of the Law 289/2002 (OPCM 3274/2003,
article 3, paragraph 2);
• further financial resources found by the DPC, according to the Regions (OPCM
3274/2003, article 3, paragraph 3).
5.4.2.3.3 Fund for extraordinary interventions for the reduction of seismic risk
A Fund of the President of the Council of Ministers (PCM) useful for the extraordinary interventions
to reduce the seismic risk is established by the Law 24th November 2003 no. 326. It allocates Euro
73.487.000,00 for the year 2003.
The OPCM 8th July 2004 no. 3362 regulates the procedures of activation of the previously mentioned
Fund (OPCM 3362/2004, article 1, paragraph 1). It allocates Euro 100.000.000,00 for the year 2004
and Euro 100.000.000,00 for the year 2005. For each of these two years, Euro 67.500.000,00 are
allocated for interventions of regional reference, and Euro 32.500.000,00 are allocated for
interventions of state reference (OPCM 3362/2004, article 1, paragraph 2).
Moreover, the intervention typologies that can be referred to the Fund financing are defined (OPCM
3362/2004, article 1, paragraph 4). In particular, they are
• technical checks;
• upgrading or improvement.
The rate of the financing that are allocated for the technical checks is established by each Region
(OPCM 3362/2004, article 1, paragraph 5).
The Fund financing is referred to the interventions in zones 1, 2 and 3, on structures built before 1984
and on important buildings, as indicated at § 1.2.1 (OPCM 3362/2004, article 1, paragraph 7).
The subdivision of the first part of financing (Euro 100.000.000,00 for the year 2004) is established on
the basis of the seismic risk (OPCM 3362/2004, article 2, paragraph 1). The subdivision is reported in
the TABLE 5.8.
TABLE 5.8. Subdivision of the Fund financing for the year 2004
REGION
Piemonte
Valle d’Aosta
Lombardia
PERCENTAGE
0,86 %
0,01 %
3,02 %
59
AMOUNT (Euro)
580.317,00
7.237,00
2.040.303,00
Prov. Autonoma of Bolzano
Prov. Autonoma of Trento
Veneto
Friuli-Venezia Giulia
Liguria
Emilia-Romagna
Toscana
Umbria
Marche
Lazio
Abruzzo
Molise
Campania
Puglia
Basilicata
Calabria
Sicilia
Sardegna
TOTAL
0,00 %
0,63 %
5,96 %
2,43 %
1,27 %
8,26 %
8,95 %
2,49 %
4,32 %
11,03 %
3,39 %
0,93 %
17,22 %
5,45 %
1,91 %
7,53 %
14,32 %
0,00 %
100,00 %
0,00
425.969,00
4.026.129,00
1.642.901,00
860.160,00
5.578.731,00
6.040.875,00
1.680.831,00
2.916.281,00
7.446.927,00
2.287.573,00
629.237,00
11.624.262,00
3.676.077,00
1.291.937,00
5.080.090,00
9.664.163,00
0,00
67.500.000,00
Within 120 days from the publication of the OPCM 3362/2004 the Region had to communicate to the
DPC a temporal plan for the structural checks and a plan of upgrading and improvement, with the
indication of the rate that could be financed by the implementing subject and the one by the beneficial
owner (OPCM 3362/2004, article 2, paragraph 2).
The Regions can to use a quantity of resources exceeding the amount fixed by the Government, if
deeper analyses are needed. The amount can’t exceed 20% over the value established by the
Government. In presence of “serious and present” seismic risk, the limit can be exceeded, and the
Region can use financial resources taken by its own budget (OPCM 3362/2004, article 3, paragraph 1).
Referring to the buildings, the financial resources are allocated through the definition of a conventional
cost (OPCM 3362/2004, Annex 2). Then, only the Government, on the basis of the seismic zone
where the building is located, assigns a fraction of this conventional cost. The remaining rate is
chargeable to the beneficial owner.
Buildings checks
The conventional costs for buildings checks is defined on the basis of the total volume (V) of the
building, according to the TABLE 5.9.
TABLE 5.9. Unit conventional cost for building check according to OPCM 3362/2004
VOLUME (mc)
< 10.000
10.000 – 30.000
30.000 – 60.000
60.000 – 100.000
> 100.000
UNIT CONVENTIONAL COST (Euro / mc)
2,50
(min 3.000,00 Euro / building)
1,80 for the volume exceeding 10.000 mc
1,20 for the volume exceeding 30.000 mc
0,60 for the volume exceeding 60.000 mc
0,30 for the volume exceeding 100.000 mc
The Government provides the 50% of the intervention conventional cost if the buildings are in seismic
zones 1 or 2, while it provides the 30% of the intervention conventional cost if the buildings are in
seismic zone 3.
Buildings upgrading
It is considered a conventional cost equal to 150,00 Euro/mc. The Government provides only a fraction
of the cost of the intervention. This fraction is calculated on the basis of the parameter α (to be chosen
60
among the values αu and αe, depending on probabilistic considerations related to the seismic hazard).
The Government provides financing in the measure of:
• 100% of the whole conventional cost if α < 0,2;
• 0% of the whole conventional cost if α> 0,8;
380 − 400α
•
% of the whole conventional cost if 0,2 < α < 0,8.
3
Buildings improvement
The conventional cost for buildings improvement is equal to 150,00 Euro/mc. The Government
provides the 60% of the whole conventional cost of the intervention in seismic zone 1, the 50% in
seismic zone 2, the 30% in seismic zone 3.
A synthesis of the Italian rules is shown by FIGURES 5.18 and 5.19.
Within 5 years (since 2003) the owners of strategic and relevant buildings must check
them from the seismic point o f view
Department of
Civil Defence (DPC)
Regions
Buildings of state reference
Buildings of regional reference
•
Temporal plan of the necessary seismic checks
•
List of buildings to be checked
•
Plan of upgrading and improvement interventions
Financial resources
Fund of the President of the
Council of Ministers
for extraordinary interventions
•
•
Owners
YEAR 2004: 67,5 million Euro for buildings
of regional reference; 32,5 million Euro for
buildings of state reference (total 100 million
Euro for the year 2004)
YEAR 2005: 67,5 million Euro for buildings
of regional reference; 32,5 million Euro for
buildings of state reference (total 100 million
Euro for the year 2005)
FIGURE 5.18. Intervention framework according to OPCM 3274/2003 and 3362/2004
61
REGIONS:
-Temporal plan of the necessary structural checks
-Plan of upgrading and improvement interventions
with the indication of the conventional cost of the interventions, calculated on the basis
of the Annex 2 of the OPCM 3362/2004
to
Department of Civil Defence
Special Orders of the President of the Council of Ministers
for the individuation of the interventions to be realized
Structural checks
FINANCING
Fund / Owners
30%
50%
50%
50%
70%
Upgrading
Seismic zone 1
Improvement
50%
Seismic zone 3
Seismic zone 2
The rate of state financing is depending on the collapse risk
30%
40%
50%
50%
60%
70%
Seismic zone 1
Seismic zone 2
Seismic zone 3
FIGURE 5.19. Intervention framework on buildings of regional reference
62
5.4.2.5 Maroc
Following the 1960 Agadir earthquake, Morocco adopted a first seismic buiding code "Normes
Agadir 1960”, through the royal law n° 2-60-893 of the 2nd Rajeb 1380 (December 21, 1960). The
application of this code was limited geographically to the Agadir region.
Between 1960 and 2002 (42 years), no official nationwide seismic code “RPS-2000” was applied. In
the year 2002, a new seismic code was approved through the law n° 2-02-177 of 9 Hija 1422 (February
22, 2002). Thus, the application of this code became effective in september 2002. This code is based
on two major axes: a- building classes & b- seismic zoning (FIGURE 5.20).
A = 0.01g
A = 0.08g
A = 0.16g
FIGURE 5.20. Seismic zones in Morocco as defined in the seismic building code “RPS-2000”.
The RPS-2000 main seismic zones and the corresponding acceleration coefficients with a 10%
exceedance probability in 50 years are shown on FIGURE 5.20. Thus, three zones are identified with
accelerations that vary between 1%g and 16%g.
Following the February 24, 2004, Al Hoceima earthquake, this code is presently under revision.
5.4.2.6 Romania
The following building codes are presently related to the design of earthquake resistance of the new
buildings in Romania:
P100-92 Code for seismic design of civil and industrial buildings. Ministry of Transport,
Construction and Tourism, MTCT, Bucharest, 1992, 152p (English version 1993, 151p).
Chapters 11, 12 were modified in 1996, 50p;
P100-04 Code for earthquake resistance of buildings. Draft which follows EUROCODE 8
format and requirements for the new buildings, 2004.
A tentative code for earthquake resistance of existing buildings is under preparation at UTCB and
should be matter of concern for the World Bank Project on Risk Mitigation in Romania, Earthquake
Risk Reduction Component (2004-2009).
The evolution of the seismic codes and zonation map standards in the last 65years in Romania is
summarized in TABLE 5.10.
63
TABLE 5.10. Classification of codes for design of earthquake resistance of buildings and standards for
seismic zonation of Romania (1940-2005)
Period
Code for earthquake
Seismic
resistance of structures zonation standard*
Pre-code,
Prior to the 1940 earthquake P.I. - 1941
P.I. – 1941
before 1963
and
I - 1945
I – 1945
Prior to the 1963 code
STAS 2923 - 52
Low-code,
Inspired by the Russian
P 13 - 63
STAS 2923 - 63
1963-1977
seismic practice
P 13 - 70
Moderate-code, After the great 1977
P 100 - 78
STAS 11100/1 - 77
1977–1990
earthquake
P 100 - 81
Moderate to
After the 1986 and the 1990 P 100 - 90
STAS 11100/1 - 91
high-code,
earthquakes
P 100 – 92
SR 11100/1 - 93
after 1990
P 100 – 04 (draft)
* The intensity scale used in Romania is MSK - 64 scale (STAS 3684 - 63, STAS 3684 - 71)
Classification of building age as function of seismic codes inter-benchmark periods provides
immediate information about the level of seismic knowledge incorporated into the building design.
The RISK-UE project, WP1 gives the classification in TABLE 5.11. of building stock age in 7
European towns, as well as the classification of codes inter-benchmark periods in TABLE 5.12.
TABLE 5.11. Building stock age versus seismic codes inter-benchmark periods
Town
Barcelona
Bitola
Bucharest
Catania
Nice
Sofia
Thessaloniki
Seismic codes inter-benchmark periods
Pre-code
Low-code
Moderate code
79%
21%
-48%
29%
23%
30%
30%
40%
92%
8%
75%
25%
Data not available
20%
50%
30%
TABLE 5.12. Code for earthquake resistance of structures
Country
Spain
FYR
Macedonia
Romania
Italy
France
Bulgaria
Greece
Pre-code
< 1968
≤1948 and
PTP-2
≤1964
≤1941 and
≤1963
P13-63
< 1981
≤ 1955
≤1964
< 1959
Level of knowledge incorporated into seismic design
Moderate-advanced
Low-code
Moderate code
code
1968....
1964-1981
1981-1990
1990 Æ present
1963-1977
1977-1992
1992 Æ present
1956-1969
1964-1972
1959- 1984
1970-1992
1972-1987
1984- 1995
1981 Æ present
1993 Æ present
1987 Æ present
1995 Æ present
One might observe the precode buildings might represent even more than 90% of total stock in Catania
and maybe less than 20% of total stock in Thessaloniki; but moderate/advanced code buildings are
generally less than 25% of total stock in many countries in spite the Bucharest new buildings represent
about 40 % of total number of buildings in the city TABLE 5.13. and TABLE 5.14.
64
TABLE 5.13. Housing units in Bucharest according to the periods of validity of various seismic codes
Seismic
code
benchmark periods
before 1941
1941-1963
1963-1970
1970-1978
1978-1992
1992-2000
Total
(Bucharest Report for UN Radius Project, 1999)
inter- Housing units built during inter- % housing units built during
benchmark periods
inter-benchmark periods
168,556
21.5
~22%
69,702
8.9
~38%
110,669
14.2
119,625
15.3
292,594
37.4
~ 40%
21,282
2.7
782,428
100%
TABLE 5.14. Distribution of tall buildings in Bucharest by period of construction and number of
storeys (Bucharest Report for UN Radius Project, 1999)
< 1945
1946 - 1963 1964 -1970
1971-1977 1978 - 1990
Storeys 1)
9
89
104
45
88
1550
10
17
77
137
51
177
11
63
70
447
830
1063
>11
9
34
7
87
72
Total
486
434
657
1091
2970
1)
Including the ground floor
1990 -1992
21
4
5
1
36
5.4.2.6 Turkey
Seismic regulations in Turkey are developed in conjunction with a nation-wide zone map and
associated codes. The first seismic regulation in Turkey was developed in 1944 with two zones,
motivated by severe damage due to the 1939 Erzincan earthquake that killed more than 30,000 people.
The national zone map has been revised three times since then. Changes are associated with increment
of zones, increment in fundamental base shear coefficient, and inclusion of more coefficients such as
structural type, ground type, spectral, and importance, as shown in TABLE 5.15. The current seismic
building code, “Regulations for Structures to Be Built in Disaster Areas,” was established by the
Ministry of Public Works and Settlements as another by-law in pursuant to the Disaster Law.
The latest revision of the seismic zone map was made in 1996. In the previous 1972 map, the boundary
of each zone was made based on observed ground motions. However, in the new map, the boundary of
each zone is based on calculations of the maximum effective acceleration for a return period of 475
years.
FIGURE 5.21 shows the latest 1996 revision of the national seismic zone map. Because of the
existence of North Anatolian fault, the highest risk area (zone I) extends in the east-west direction in
Turkey. According to the map, the southeastern part of the Istanbul Province on the Asian side is
located in one I, while most of the European side of the province is located from zone II to zone IV.
65
TABLE 5.15. Development of Seismic Regulation in Turkey (Kobayashi, K et al., 2001)
FIGURE 5.21. National Seismic Zone Map as Revised in 1996 (Ministry of Public Works and
Settlements)
66
5.5. SUCCESSFUL INTERVENTION FOR CULTURAL HERITAGE CONSTRUCTIONS
5.5.1 Strengthening of a Church Using Steel Members
5.5.1.1 Description of measures
The Church of the Ascension of Christ is the Metropolitan Church of Koropi town, located 30 km out
of Athens at the area of Messogeia. The construction of the Church started in 1858 and lasted six years
and ten months. The Church belongs to the category of cruciform basilicas' with dome. It is made of
limestone masonry walls, of 0.8-1.0 m thickness, on a shallow foundation and masonry arches made
from light sandstone. The quality of masonry is moderate, characterized by the small size of stones.
The Church was built with a defect at the NE main column having a vertical eccentricity of about 0.15
m. Moreover, in 1973 they added a second taller reinforced concrete dome to the church, so as to be
seeing from the remote edges of the expanding town.
In its lifetime the Church has suffered several strong earthquakes, the most recent ones being the one
in 1981 [www.itsak.gr] and recently in September 1999 the Athens earthquake
[www.itsak.gr/report.htm] originated from a nearby fault at the mountain Parnes. The accumulated
damage from all these events and mainly from the last earthquake were major cracks in the walls,
cracks almost in all arches, major cracks at the marble column capitals and extensive smaller cracks at
the tipper part of the church, indicating a uniform tendency of disorganization of the masonry.
Based on this evidence, the authorities closed the Church and asked for repair and strengthening
measures for the structure. An analysis of the structure, modeling all main structural components, was
performed on the basis of Finite Element Method using Nastran Code for the existing structure and the
strengthened one (Figures 5.22., 5.23.).
FIGURE 5.22. Finite Element model of the exterior masonry
67
FIGURE 5.23. Finite element model of the interior arches with the added line steel members
The aim was first to correlate the areas of critical stresses in the model, with the damaged areas in the
structure and obtain confidence on the model and then to identify ways to improve the performance of
the structure in future seismic events.
The properties of the materials were determined by appropriate testing. Plate and membrane elements
were used for the masonry walls and arches, whereas beam elements for the main columns. An
equivalent linear static analysis with earthquake forces based on the design spectrum of the Greek code
was performed. This pointed out areas of excessive stresses in close agreement with the observed
damage. This was specifically true for the east part of the sanctuary.
The dynamic characteristics of the existing structure, apart from the different sway modes, revealed the
importance of vertical modes of vibration in the area of the double dome at relatively low frequencies.
The spectral analysis that followed accounted also for these vertical mode shapes, so as to understand
and estimate the influence of the added second dome to the entire structure. The fundamental frequency
is 3.77 Hz and the mode shape is along the lateral direction (FIGURE 5.24.). The fourth mode that
contributes mainly in the area of the side entrances and the dome is presented in FIGURE 5.25.
FIGURE 5.24. Fundamental mode at 3.77 Hz
FIGURE 5.25. Fourth Mode, with localized
motion at Side Entrances
The analysis of the existing structure was followed by a series of different scenarios aiming to control
the dynamic behavior of the structure and to redistribute the stresses so as to avoid potential premature
failure modes, as for example collapse of the domes and/or side entrances. All these alternatives were
based on adding steel members. The decided layout is presented in FIGURES 5.26. and 5.27.
68
FIGURE 5.26. Plan View of the Church with
strengthening steel members
FIGURE 5.27. Section A-A of the
Church
The aim is to control the action of arches by constructing a grid of hollow sections SITS 120/120/7.1 at
the level of the base of the arches together with the inclined struts at the side aisles (FIGURES 5.28.5.30.). The steel members controlled the horizontal movement of the central columns without
destructing the greatness of the area underneath the dome. A lighter system with only tensile members
didn't offer adequate restrain on the rotations at the base of the arches, which was needed for the
protection of the marble capitals. All steel members were welded in situ and anchored in areas of the
masonry that were previously strengthened locally. After the completion of the steelwork the Church
opened before the Easier of 2000.
The design of all the additional steel members was based on Eurocode 3, where the diagonal members
are designed both in tension and compression. These members are connected to the arches with
rectangular strips made of 300x30 mm steel plates anchored to the masonry with epoxy resin dowels
(FIGURE 5.31), while the gaps were filled with non-shrinking cement mortar. Moreover, the motion
of the domes was controlled effectively by the inclined struts, which transfer part of the load to the
external piers and prevent overloading of the central columns that carry the loads safely without any
major strengthening.
Although this Church officially is not a monument, all suggested measures considered the Church as
such. Additional strengthening measures were decided and applied that consist of a) strengthening of
the masonry walls and arches by injection of grout of particular composition, so as to assure
penetration as well as adequate bonding, b) repair and strengthening of the marble column capitals
with epoxy resins and mortars and bronze hoop ties and c) strengthening of the main piers of the axes
1 and 2 of FIGURE 5.32 at the north and south side with carbon fibber composites.
69
FIGURE 5.28. Steel strengthening at the arch base
FIGURE 5.29. Steel members at the right aisle
FIGURE 5.30. Steel members at the SE Column
70
FIGURE 5.31. Epoxy resin anchor bolts at
column capital base
FIGURE 5.32. Bronze hoop ties at column
The injection of grout at low pressure was performed in zones that were elevated gradually. The grid
of injection points was dense from the outside (0.2 to 0.5 m) and more sparse from the inside not to
damage the hagiography. The cracks in the monolithic marble column capitals were investigated with
endoscopic photographs to measure their extent and width. The cracks were sealed with epoxy mortar
and epoxy resin, mixed with marble powder of different grain size in relation to the crack width,
injected from a dense net of injection points.
To increase the load carrying capacity of the column capitals slightly prestressed bronze hoop strips
were place at appropriate positions. To secure further the piers of the north and south entrance
strengthening with carbon fibber composites was applied in two vertical and two horizontal strips at
each side.
FIGURE 5.33. South view after completion of grout injection
Repair and strengthening of the Church of the Ascension of Christ using mainly steel members turned
out to be very effective, practical and relatively fast in increasing the load carrying capacity and
enhancing the dynamic behavior of the structure.
71
5.5.2 The Cases of Toscana and Campania Regions (Italy)
Toscana and Campania Regions are here considered as examples of application of the measures
adopted by the Government for the reduction of seismic risk.
5.5.2.1 The case of Toscana Region
Toscana Region assigned the 100% of the financing of 2003 and the 30% of the financing for 2004
(financing deriving on the basis of the Law 23/96) for the realization of preventive interventions
against the seismic actions.
A Regional plan for the seismic checks on strategic and relevant buildings (VVSESeR) has been
defined as a consequence of the Resolution of Toscana Regional Council (GRT) 27th October 2003,
no. 1114. In particular, the considered buildings are the ones, belonging to local authorities, used for:
• instruction;
• institutions;
• local authorities;
• strategic centres for civil defence;
• hospitals.
Referring to the Fund for extraordinary interventions, presented in the previous paragraph, Toscana
Region presented to the DPC (on 16th November 2004) its “Temporal plan for technical checks” and
its “Plan of upgrading and improvement interventions”.
5.5.2.2 The case of Campania Region
Campania Region received by the Government a total of Euro 11.624.262,00. The Resolution of
Campania Regional Council (GRC) 30th December 2004 no. 2535 established that Euro 10.000.000,00
had to be allocated for the improvement of strategic public buildings and Euro 1.624.262,00 had to be
allocated for structural checks.
In the Annex of the mentioned Resolution, a list of all the buildings interested by improvement or
check interventions is presented. For each building the following information are presented:
• seismic zone
• address
• name
• structural system
• usage
• total volume
• intervention cost
• state contribution (according to OPCM 3362/2004)
• cost chargeable to the beneficial owner
The total number of improvement interventions on strategic buildings is equal to 27. The considered
masonry buildings are 22, while the remaining 5 buildings are r.c. structures. 15 of the considered
buildings have a civil function, 5 have a health function, 7 have a schooling function. The total cost of
the improvement interventions is equal to 17.884.950,00 Euro. The Government must provide
9.692.535,00 Euro, while the beneficial owners must provide the remaining 8.011.466,00 Euro.
The total number of structural checks on strategic buildings is equal to 98. Among them, the masonry
structures are 87, while r.c. structures are 11. 24 of the considered buildings have a civil function, 7
have a health function, 67 have a schooling function. The total cost of the structural checks is equal
to Euro 1.613.108,00.
72
5.5.3 Reinforcement Techniques by the Addition of a New Structure
For historical monuments, in Morocco, the procedure of restoration is generally the following:
Structural works:
• infrastructure intervention:
o intervention on foundations,
o renewal of the sewer and the electric networks, and Branching
• works in superstructure;
o Repairing masonry,
o Scouring of the existing coatings (plaster, lime or cement)
o Surfaces flattening and traditional sealer (rendering),
o Shape of slopes,
o Watertightness and struggle against humidity: multilayered tightness and protection of the
tightness in Zellige (tiles),
Secondary Works:
• Restoration of sculpted plasters;
• Revetment in Zellige (coating with tiles) of walls and floors,
• Restoration of the structural wood,
• Plumbing and sanitary,
• Electricity restoration,
• Painting and windows-glasses;
• Cover of the patio in Plexiglas
In structural problem cases, backing techniques consist generally either by the setting up of a new
reinforcement structure made of steel, or out of wood (FIGURE 5.34).
FIGURE 5.34.Setting up of reinforcement structure in wood to avoid the collapse of walls for
neighbouring houses in the street in the old Medina of Fez (Morocco); a reversible intervention.
73
5.5.4 Brancusi Endless Column in Romania
Targu Jiu in Romania
FIGURE 5.35. Brancusi Endless Column at Targu Jiu, Romania
The reversible restoration of Constantin Brancusi’s monumental Endless Column in
Romania, has been completed on-site on December 17th, 2000. The 29.8m steel column
cast-iron 1.8m-high modules was originally installed in Targu Jiu in 1938. The
Government, the World Bank, the World Monuments Fund and other institutions have
supported the restoration.
Târgu-Jiu,
spine with
Romanian
financially
"It is, for Romania, for the Ministry of Culture, for the inhabitants of Târgu-Jiu, and also for our
partners — The World Bank and World Monuments Fund — a great event," said Mr. Caramitru, the
Romanian Minister of Culture in December 2000. "We are happy to state that this important project,
aimed at the restoration and preservation of one of the most outstanding open-air works of art of the
20th century, has been implemented by respecting Brancusi's original work i.e. keeping the original
steel spine and original cast-iron modules as they were designed by the artist and by the engineer.
In 1998, the Romanian Government and WMF successfully established a partnership with the World
Bank to finance the restoration of the entire ensemble. The World Bank committed $2.6 million to the
overall project in Tg. Jiu in the form of a loan to the Romanian government. WMF was able to raise
over $600,000 from many sources including companies and private individuals. The Romanian
Government provided the rest of the cost of restoration.
"While physically the Endless Column is the simplest structure WMF has ever dealt with," said John
Stubbs WMF Vice President for Programs, "Its restoration was one of the most complex, especially
from a theoretical standpoint."
The Technical University of Construction Bucharest report entitled “Wind action on Brâncusi Endless
Column at Tg. Jiu, Romania, according to the wind loading codes from European Union, USA and
Romania” in 2000, was the technical and theoretical justification for the structural rehabilitation of the
Endless Column spine by keeping the original steel core.
74
The adverse alternative –which has been defeated - was the substitution of the original steel core by a
new stainless steel solution.
The Endless Column consists of three components:
i)
Foundation, made of two concrete blocks (4.50x4.50x2.00m and 3.50x3.50x5.00m) with
metallic anchorage fixed with bolts;
ii)
Central steel spine 28.90 m high, with a square cross-section made up of angle irons and
steel plates connected with rivets and screws; at the base of the spine 5.50 m from 28.9 are
filled up with concrete;
iii)
17 modules, shaped as double pyramid with curved surface made of cast iron and,
measuring 180 cm height and 45–90 cm width.
FIGURE 5.36. The lower part of the spine, before and after the tanning
75
+28.90
CI 4-4
+19.70
CI 3-3
+11.70
CI 2-2
+0.56
~
~
CI 1-1
Weight of the structure 14947 daN;
Weight of the modules 14226 daN;
Weight of interior concrete 1408 daN;
Total weight of the column 30581 daN;
FIGURE 5.37. Characteristics of the OL 37 steel Endless Column structure
(central spine, inside Column)
76
The structural model consists of 32 FRAME elements evenly distributed on the height of the column.
Each frame element has 90 cm in length.
The results of the modal analysis performed with SAP90 computer code are given TABLE 5.16. Other
results provided by former analytical studies or on site measurements are also presented.
TABLE 5.16. Fundamental period of vibration for Endless Column, in seconds
Steel spine, without
modules
Endless Column with
modules
Measured
on site after
strengthening,
UTCB,
Dec. 2000
Modal
analysis,
UTCB,
2000
Measured
on site,
INCERC, 1985
Modal
analysis,
INCERC, 1984
1.28
1.43
-
-
1.95
1.99
1.80
1.90
The largest fundamental period of vibration (1.99s) has been selected for Endless Column dynamic
response to wind, in order to get the most severe response.
FIGURE 5.38. Vibration measurements at Endless Column site, December 2000
Y
Y
X
X
Case 1
X
Case 2
Y
X
Y
Y
X
Case 3
FIGURE 5.39. Arrangement of the sensors
Dec. 3rd, 2000
FIGURE 5.40. Arrangement of the sensors
Dec. 14th, 2000
77
The value of the aerodynamical coefficient is confirmed by the wind tunnel tests at University of
Florence led by Prof. Giovanni Solari, University of Genoa which gives cf = 1.1 for wind normal to
face (average slenderness of the model about 8); According to American and European codes the tests
value needs an increase of about 25-30% to take into account the actual slenderness of the Column.
CD
1.6
1.5
1.4
1.3
1.2
1.1
1
0.9
0.8
-60
-55
-50
-45
-4 0
-35
- 30
-2 5
-20
- 15
-10
-5
0
5
10
15
20
25
30
35
40
45
50
55
60
ang o lo [g rad i]
FIGURE 5.41. Wind tunnel test model for Endless Column at Florence University, Italy
Vibration measurements of the Endless Column in Targu Jiu, December 2000
78
5.5.5 Rehabilitation and Conservation of Historic Cairo: Managerial Strategies
Historic Cairo, proclaimed as a world
heritage site by UNESCO, is receiving
national attention. In 1995, UNDP
financed a study for the rehabilitation of
Historic
Cairo.
Consequently,
a
Presidential
Committee
with
representatives of all concerned authorities
has established. The committee dealt with
the occupation of 274 squatters for 105
heritage sites, with instituting a plan to
preserve 146 monuments in stages; the
first includes 43 buildings in Gamaliya,
Ghouryia, AJ-Azhar, AI-Darb Al-Ahmar(
Al- Saliba, and Ibn Tulun districts at a cost
of 350
million Egyptian pounds.
Preservation is to be conducted under the
authority of the Ministry of Culture. The
Ministry of Housing is completing two
tunnels at a cost of one billion Egyptian
pounds that will allow traffic to flow
underground freeing the AI-Azhar area to
become a pedestrian zone.
An
administrative
unit,
Historical
Preservation
Administrative
Unit
(HCPAU) and the Center of Studies and
Development of Historic Cairo, attached to
the Office of the Minister of Culture,
control the project progress. It has charged with updating the map of Cairo Islamic monuments and
creating a computerized database related to each historic structure.
The preservation and restoration adapted methodology includes specifications for documentation,
architectural drawings, studies of soil properties and subsurface water movement, material analyses,
deterioration evaluation and finally, urban rehabilitation. Historical records are studied to provide
information on the original layout, construction, and uses of the building as well as its conservation
and restoration life history. With this framework, actually, 90 historical building are under restoration
and preservation.
Assessment of the seismic vulnerability of monuments, as a complex multi-disciplinary task, is
initiated as one step of stability analysis & conservation project of historical buildings that includes the
following steps:
• Immediate measures to maintain stability and prevent total or partial collapse.
• Comprehensive study to identify critical elements and define numerical parameters (historical
Studies, Surveying & architectural detailing, geotechnical, materials evaluation,
infrastructure/utilities, site observations and monitoring)
• Structural assessment and studying various retrofitting schemes
79
•
Seismic issues, modal analysis vs. time-history analysis: historical events and their effect on
the monument, current seismic code provisions and its applicability to historical buildings.
Assessing alternatives for strengthening of structure (traditional methods, new technology, and
reversibility of intervention). Special features in monument studies should be evaluated, these include
as bonding of structural materials, statical system, load-bearing slender walls (multi-leaf), stone arches
and ties, domes, minarets. Number of intervention modes may be considered:
Soil strengthening
–
Soil injection
Soil reinforcement by micropiles
–
–
Soil stabilization by cement or lime components
Foundation strengthening
–
Increasing the bearing area
–
Injecting foundations
–
Utilize deep foundations (micropiles)
Material strengthening
–
Injection.
–
Replace bonding material.
–
Replace stone/brick
System strengthening
–
Introduce new walls
–
Strengthen existing walls
–
Improve or introduce confinement.
80
REFERENCES
Reference Literature
ASCE 7-93, 1993, ASCE7-95, 1995 and ASCE7-98, 2000. Minimum design loads for buildings and other structures.
American Society of Civil Engineers, New York
European Prestandard ENV 1991-2-4, 1994. EUROCODE 1: Basis of design and actions on structures, Part 2.4 : Wind
actions, CEN
Eurocode 8 - Design provisions for earthquake resistance of structures, 1994. Part 1-1: General rules - Seismic actions and
general requirements for structures. CEN, European Committee for Standardization, Oct.
Guidelines for Seismic Retrofit of Existing Reinforced Concrete Buildings, 2001. Published by The Japan Building
Disaster Prevention Association, Translated by BRI. 91 pages
Ministry of Environment, Land Use and Public Works - Greek Earthquake Planning and Protection Organization, Greek
Seismic Code (EAK2000 – modifications 2003)
Standard for Seismic Evaluation of existing Reinforced Concrete Buildings, 2001. Published by The Japan Building
Disaster Prevention Association, Translated by BRI. 76 pages.
Technical Manual for Seismic Evaluation and Eeismic Retrofit of Existing Reinforced Concrete Buildings, 2001. Published
by The Japan Building Disaster Prevention Association, Translated by BRI. 85 pages.
The Burra Charter The Australia ICOMOS charter for the conservation of places of cultural significance, 1999.
The Getty Conservation Institute, Incentives for the Preservation and Rehabilitation of Historic Homes in the City of Los
Angeles, A Guidebook for Homeowners, 2004
2001 California Historical Building Code, California Code of Regulations, Title 24, Part 8 published by
International Conference of Building Officials 5360 workman mill road whittier.
ICOMOS, 2003 Recommendations for the analysis, conservation and structural restoration of architectural heritage
Aldea, A., Arion, C., Demetriu, S., Saito, T. (2001), Ambient vibration measurements for Brancusi Endless Column,
Internal Reports, Technical University of Civil Engineering of Bucharest
Avrami Erica, Randall Mason, Marta de la Torre, Values and Heritage Conservation Research Report for The Getty
Conservation Institute, Los Angeles, 2002
Coburn, A., Spence, R., (1992), "Earthquake protection", John Wiley & Sons., New York, 355p.
Kasai, K., 2004. Current status of Japanese passive control scheme for mitigating seismic damage to building and
equipments, Modern Urban Seismic Network in Bucharest, Romania, Proceedings of the First International
Conference on Urban Earthquake Engineering, March 8-9, 2004, Tokyo Institute of Technology, Yokohama,
Japan, 12p., p.121-133
Kasai, K., 2004. Lecture note at the IISEE, Tsukuba, Japan
Lungu, D., Aldea, A., Arion, C., Cornea, T., 2001. City of Bucharest Seismic Profile: from Hazard Estimation to Risk
Management, Earthquake Hazard and Countermeasures for Existing Fragile Buildings, Contributions from JICA
International Seminar: Bucharest, November 23-24, 2000, Lungu, D., Saito, T. (editors), Independent Film,
Bucharest, p. 43-66
Lungu, D., Aldea, A., Arion, C., 2000. "Engineering, state & insurance efforts for reduction of seismic risk in Romania" In:
Proceedings of the 12th World Conference on Earthquake Engineering, Auckland, New Zealand, Jan/Feb.
Lungu, D., Văcăreanu, R. - Wind Action on Brancusi Endless Column at Tg. Jiu, Romania according to the wind loading
code from European Union, Technical Report for the World Bank Project - Cultural Heritage, Rehabilitation of
Endless Column by Constantin Brancusi, 25 p, 2001.
Nawrotzki, P., 2005. Visco-elastic devices for the seismic control of machinery, equipments and buildings. 9th World
seminar on Seismic Isolation, Energy Dissipation and active Vibration Control of structures, Kobe, Japan, June
13-16, 2005.
Postelnicu T., at al., 2001. Guidelines For Seismic Rehabilitation, Technical University of Civil Engineering of Bucharest,
Reinforced Concrete Department, 2001
Postelnicu T., at al., 2005. Report on the Framework of the Manual for Seismic Evaluation of Existing Buildings
in Romania September, NCSRR report
Sharpe Richard, 2005. Earthquake engineering a science or an art, 2005 Personal communication.
Solari, G., Lungu, D., Bartoli, G., Righi, M., Văcăreanu, R., Villa, A, August 2002, “Brancusi Endless Column, Romania:
Dynamic response and reliability under wind loading”, The Second International Symposium on Advances in Wind
and Structures (AWAS'02), Pusan Convention Center, Pusan, Korea
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Beg, D., (2005). Report on Workpackage 4: Intervention Strategies (Slovenia contribution), FP6-2002-INCO-MPC-101,
PROHITECH project.
Chemrouk M., Attari N. E., Derradj Z., Bouzid F., (2005). Report on Workpackage 4: Intervention Strategies (Algerian
contribution), FP6-2002-INCO-MPC-101, PROHITECH project. Doc. N..15.04.01.02.
Demonceau, J.F., Jaspart J.P. (2005). Report on Workpackage 4: Intervention Strategies (Belgian contribution), FP6-2002INCO-MPC-101, PROHITECH project. Doc. N..02.04.01.01.
El Hammoumi A., Iben Brahim A, Toto A., El Mouraouah A., Kasmi M., Birouk A., (2005). Report on Workpackage 4:
Intervention Strategies (contribution of the Moroccan team), FP6-2002-INCO-MPC-101, PROHITECH project.
Doc. N.13.04.01.02.
Güneysi E. M., Sanrı I., Altay G., (2005). Report on Workpackage 4: Intervention Strategies (contribution of the Turkey
team), FP6-2002-INCO-MPC-101, PROHITECH project. Doc. N..10.04.01.02.
De Matteis G., Esposto M., Landolfo R., Mazzolani F. M., 2005. Report on Workpackage 4: Intervention Strategies (Italian
contribution), FP6-2002-INCO-MPC-101, PROHITECH project. Doc. N..01.04.01.02.
Lungu, D., Arion, C. 2005. Report on Workpackage 4: Intervention Strategies (Romanian contribution), FP6-2002-INCOMPC-101, PROHITECH project. Doc. N..08.04.01.01.
Zahabi El M., Mourad S., 2005. Report on Workpackage 4: Intervention Strategies (Egyptian contribution to WP4), FP62002-INCO-MPC-101, PROHITECH project. Doc. N..12.04.01.01.
Vayas I., Papantonopoulos K., Marinelli K., 2005. Report on Workpackage 4: Intervention Strategies, FP6-2002-INCOMPC-101, PROHITECH project. Doc. N..04.04.01.01.
WP4 MEMBERSHIP
UNINA
B
MK
GR
NA-ARC
ROPUT
ROTUB
SL
TR
EG
MOR
AL
UNICH
(PTN. No. 1)
(PTN. No. 2)
(PTN. No. 3)
(PTN. No. 4)
(PTN. No. 5)
(PTN. No. 7)
(PTN. No. 8)
(PTN. No. 9)
(PTN. No. 10)
(PTN. No. 12)
(PTN. No. 13)
(PTN. No. 15)
(PTN. No. 16)
Federico Massimo MAZZOLANI
Jean-Francois DEMONCEAU
Elena DUMOVA – JOVANOSKA, Zoran MILUTINOVIC
Ioannis VAYAS
Raffaele LANDOLFO
Victor GIONCU
Dan LUNGU
Darko BEG
Gulay ALTAY (ASKAR)
Mohamed EL ZAHABI
Aomar IBEN BRAHIM
Mohamed CHEMROUK
Gianfranco DE MATTEIS
82
LIST OF CONTRIBUTORS
Gulay ALTAY
Boğaziçi Unıversıty, Department of Civil Engineering, Istanbul, Turkey
Cristian ARION
Technical University of Civil Engineering Bucharest, Structural Safety for Natural Hazard Research Centre, Bucharest
Romania
Nasser eddine ATTARI
School of Architecture and Urbanism (EPAU), Algiers, Algeria
Darko BEG
University of Ljubljana, Faculty of Civil Engineering and Geodesy, Institute of Structures and Earthquake Engineering,
Ljubljana, Slovenia
Abdelouhad BIROUK
Centre National pour la Recherche Scientifique et Technique, Morocco
Farid BOUZID
School of Architecture and Urbanism (EPAU), Algiers, Algeria
Mohamed CHEMROUK
Université of Science and Technology Houari Boumediene, (USTHB), Algiers- ALEGRIA
Gianfranco DE MATTEIS
University of Chieti/Pescara G. d’Annunzio, PRICOS, Pescara, Italy
Jean-Francois DEMONCEAU
University of Liege, Department of Structures and Materials, Liege, Belgium
Zoubir DERRADJ
School of Architecture and Urbanism (EPAU), Algiers, Algeria
Abdallah EL HAMMOUMI
Mohamed Vth University, Agdal, Morocco
M. ESPOSTO
University of Naples Federico II, Department of Constructions and Mathematical Methods in Architecture, Naples, Italy
Esra Mete GÜNEYSI,
Boğaziçi Unıversıty, Department of Civil Engineering, Istanbul, Turkey
Sherif MOURAD
Cairo University, Engineering Center for Archaeology and Environment (ECAE) Faculty of Engineering, Cairo, Egypt
Azelarab EL MOURAOUAH
Centre National pour la Recherche Scientifique et Technique, Morocco
Aomar IBEN BRAHIM
Centre National pour la Recherche Scientifique et Technique, Morocco
Jean-Pierre JASPART
University of Liege, Department of Structures and Materials, Liege, Belgium
Mohamed KASMI
Centre National pour la Recherche Scientifique et Technique, Morocco
83
Raffaele LANDOLFO
University of Naples Federico II, Department of Constructions and Mathematical Methods in Architecture, Naples, Italy
Dan LUNGU
Technical University of Civil Engineering Bucharest, Structural Safety for Natural Hazard Research Centre, Bucharest
Romania
Katerina MARINELLI
National Technical University of Athens, School of Civil Engineering, Athens, Grecee
Federico M. MAZZOLANI
University of Naples Federico II, Department of Structural Analysis and Design, Naples, Italy
Kostas PAPANTONOPOULOS
National Technical University of Athens, School of Civil Engineering, Athens, Grecee
Işıl SANRI
Boğaziçi Unıversıty, Department of Civil Engineering, Istanbul, Turkey
El Arbi TOTO
Ibn Tofail University, Morocco
Ioannis VAYAS
National Technical University of Athens, School of Civil Engineering, Athens, Grecee
El Mohamed ZAHABI
Cairo University, Engineering Center for Archaeology and Environment (ECAE) Faculty of Engineering, Cairo, Egypt
84
Content
4.1 GENERAL & TERMINOLOGY ....................................................................................................................................1
4.2 INTERVENTION SOLUTIONS AND CRITERIA FOR SEISMIC UPGRADING & REHABILITATION OF
CONSTRUCTIONS ...............................................................................................................................................................4
4.2.1 The Repair and Strengthening Design Process......................................................................................................5
4.2.1.1 Criteria of Repair and Strengthening..................................................................................................................6
4.2.1.2 Structural investigations .....................................................................................................................................6
4.2.1.3 Damage evaluation and selection of a repair and strengthening solution..........................................................7
4.3 OPTIONS FOR INTERVENTION STRATEGY ..........................................................................................................8
4.3.1 TECHNICAL STRATEGIES ................................................................................................................................................8
4.3.1.1 Reducing seismic requirements ...........................................................................................................................9
4.3.1.2 Improving the mechanical characteristics of the construction............................................................................9
4.3.1.3 Choice of intervention systems ..........................................................................................................................10
4.3.2 REPAIR & STRENGTHENING OF EXISTING BUILDINGS ...................................................................................................10
4.3.2.1 Strengthening unreinforced masonry buildings ................................................................................................11
4.3.2.2 Strengthening reinforced concrete buildings ....................................................................................................12
4.3.2.3 Repair and strengthening of historical buildings ..............................................................................................14
4.3.2.4 Materials and construction techniques .............................................................................................................16
4.3.2.5 Foundations.......................................................................................................................................................20
4.3.3 PASSIVE CONTROL OF STRUCTURES—ENERGY ISOLATING AND DISSIPATING DEVICES ..................................................21
4.3.3.1 Introductory remarks.........................................................................................................................................21
4.3.2.2 Isolation from seismic motion ...........................................................................................................................22
4.3.3.3 Analysis concepts of damage controlled structures ..........................................................................................24
4.3.3.4 Seismic isolation using flexible bearings ..........................................................................................................25
4.3.3.5 Rocking structures.............................................................................................................................................25
4.3.3.6 Energy dissipators for seismically-isolated structures.....................................................................................26
4.3.3.7 Energy dissipators for non-isolated structures .................................................................................................26
4.3.4 CONCLUSIVE REMARKS ...............................................................................................................................................31
4.4 COUNTRY SEISMIC LEGISLATION & ACTIONS FOR SEISMIC INTERVENTION ON
CONSTRUCTIONS .............................................................................................................................................................31
4.4.1 SEISMIC RISK MANAGEMENT LEGISLATION AND ACTIONS .............................................................................................31
4.4.1.1 Algeria...............................................................................................................................................................31
4.4.1.2 Belgium .............................................................................................................................................................33
4.4.1.3 Egypt .................................................................................................................................................................33
4.4.1.4 Italy ...................................................................................................................................................................34
4.4.1.4 Maroc ................................................................................................................................................................38
4.4.1.5 Romania ............................................................................................................................................................39
4.4.1.6 Slovenia.............................................................................................................................................................42
4.4.1.7 Turkey................................................................................................................................................................42
4.4.2 BUILDING CODES AND CODES INTER-BENCHMARK PERIODS ........................................................................................54
4.5. SUCCESSFUL REVERSIBLE INTERVENTION FOR CULTURAL HERITAGE CONSTRUCTIONS ..........67
4.5.1 STRENGTHENING OF A CHURCH USING STEEL MEMBERS..............................................................................................67
4.5.1.1 Description of measures....................................................................................................................................67
4.5.2 THE CASES OF TOSCANA AND CAMPANIA REGIONS (ITALY)...........................................................................................72
4.5.2.1 The case of Toscana Region..............................................................................................................................72
4.5.2.2 The case of Campania Region...........................................................................................................................72
4.5.3 REINFORCEMENT TECHNIQUES BY THE ADDITION OF A NEW STRUCTURE ......................................................................73
4.5.4 BRANCUSI ENDLESS COLUMN IN ROMANIA...................................................................................................................74
4.5.5 REHABILITATION AND CONSERVATION OF HISTORIC CAIRO: MANAGERIAL STRATEGIES .................................................79
REFERENCES .....................................................................................................................................................................81
85