Download (from: http://en.wikipedia.orghttp//uk.wikipedia.org//w) THE SECOND

(from: http://en.wikipedia.orghttp//uk.wikipedia.org//w)
THE SECOND TERM: PART I
Contents
1 Types of construction projects
1.1 Building construction
1.2 Industrial construction
2 Construction processes
2.1 Design team
2.2 Financial advisors
2.3 Legal considerations
2.4 Interaction of expertise
2.5 Procurement

2.5.1 Traditional

2.5.2 Design and build

2.5.3 Management procurement systems
3 Authority having jurisdiction
4 Construction careers
5 History
6 See also
7 References
8 External links
Building engineering
In the fields of architecture and civil engineering, construction is a process that consists of the
building or assembling of infrastructure. Far from being a single activity, large scale construction is a
feat of multitasking. Normally the job is managed by the project manager and supervised by the
construction manager, design engineer, construction engineer or project architect. For the successful
execution of a project, effective planning is essential. Those involved with the design and execution of
the infrastructure in question must consider the environmental impact of the job, the successful
scheduling, budgeting, site safety, availability of materials, logistics, inconvenience to the public
caused by construction delays, preparing tender documents, etc.
Types of construction projects
In general, there are three types of construction:
1.
Building construction
2.
Heavy/civil construction
3.
Industrial construction
Each type of construction project requires a unique team to plan, design, construct, and maintain the
project.
1
Building construction
Building construction for several apartment blocks. The blue material is insulation cladding, which will be covered
later.
A large unfinished building
Building construction is the process of adding structure to real property. The vast majority of building
construction projects are small renovations, such as addition of a room, or renovation of a bathroom.
Often, the owner of the property acts as laborer, paymaster, and design team for the entire project.
However, all building construction projects include some elements in common - design, financial, and
legal considerations. Many projects of varying sizes reach undesirable end results, such as structural
collapse, cost overruns, and/or litigation reason, those with experience in the field make detailed plans
and maintain careful oversight during the project to ensure a positive outcome. Building construction
is procured privately or publicly utilizing various delivery methodologies, including hard bid, negotiated
price, traditional, management contracting, construction management-at-risk, design & build and
design-build bridging.
Trump International Hotel and Tower (Chicago)
May, 23, 2006
September 14, 2007
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Residential construction practices, technologies, and resources must conform to local building
authority regulations and codes of practice. Materials readily available in the area generally dictate the
construction materials used (e.g. brick versus stone, versus timber). Cost of construction on a per
square metre (or per square foot) basis for houses can vary dramatically based on site conditions,
local regulations, economies of scale (custom designed homes are always more expensive to build)
and the availability of skilled tradespeople. As residential (as well as all other types of construction)
can generate a lot of waste, careful planning again is needed here. The most popular method of
residential construction in the United States is wood framed construction. As efficiency codes have
come into effect in recent years, new construction technologies and methods have emerged.
University Construction Management departments are on the cutting edge of the newest methods of
construction intended to improve efficiency, performance and reduce construction waste.
Construction of the Havelock City Project in Sri Lanka.
Construction of Phase-1 of the Havelock City Project in Sri Lanka.
Building construction is the process of adding structure to real property. The vast majority of building
construction projects is small renovations, such as addition of a room, or renovation of a bathroom.
Often, the owner of the property acts as laborer, paymaster, and design team for the entire project.
However, all building construction projects include some elements in common - design, financial, and
legal considerations. Many projects of varying sizes reach undesirable end results, such as structural
collapse, cost overruns, and/or litigation reason; those with experience in the field make detailed
plans and maintain careful oversight during the project to ensure a positive outcome.
Building construction is produced privately or publicly utilizing various delivery methodologies
including hard-bid, negotiated price, traditional management-at-risk design build and design build
bridging
Industrial construction
Industrial construction, though a relatively small part of the entire construction industry, is a very
important component. Owners of these projects are usually large, for-profit, industrial corporations.
These corporations can be found in such industries as medicine, petroleum, chemical, power
3
generation, manufacturing, etc. Processes in these industries require highly specialized expertise in
planning, design, and construction. As in building and heavy/highway construction, this type of
construction requires a team of individuals to ensure a successful project.
Construction processes
Design team
Shasta Dam under construction
In the modern industrialized world, construction usually involves the translation of paper or computer
based designs into reality. A formal design team may be assembled to plan the physical proceedings,
and to integrate those proceedings with the other parts. The design usually consists of drawings and
specifications, usually prepared by a design team including the client architects, interior designers,
surveyors, civil engineers, cost engineers (or quantity surveyors), mechanical engineers, electrical
engineers, structural engineers, and fire protection engineers. The design team is most commonly
employed by (i.e. in contract with) the property owner. Under this system, once the design is
completed by the design team, a number of construction companies or construction management
companies may then be asked to make a bid for the work, either based directly on the design, or on
the basis of drawings and a bill of quantities provided by a quantity surveyor. Following evaluation of
bids, the owner will typically award a contract to the lowest responsible bidder.
Apartment is under counstruction in Daegu, South Korea.
The modern trend in design is toward integration of previously separated specialties, especially among
large firms. In the past, architects, interior designers, engineers, developers, construction managers,
and general contractors were more likely to be entirely separate companies, even in the larger firms.
Presently, a firm that is nominally an "architecture" or "construction management" firm may have
experts from all related fields as employees, or to have an associated company that provides each
necessary skill. Thus, each such firm may offer itself as "one-stop shopping" for a construction
project, from beginning to end. This is designated as a "design Build" contract where the contractor is
given a performance specification, and must undertake the project from design to construction, while
adhering to the performance specifications.
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Construction of a pre-fabricated house
Several project structures can assist the owner in this integration, including design-build, partnering,
and construction management. In general, each of these project structures allows the owner to
integrate the services of architects, interior designers, engineers, and constructors throughout design
and construction. In response, many companies are growing beyond traditional offerings of design or
construction services alone, and are placing more emphasis on establishing relationships with other
necessary participants through the design-build process. The increasing complexity of construction
projects creates the need for design professionals trained in all phases of the project's life-cycle and
develop an appreciation of the building as an advanced technological system requiring close
integration of many sub-systems and their individual components, including sustainability. Building
engineering is an emerging discipline that attempts to meet this new challenge.
Financial advisors
Many construction projects suffer from preventable financial problems. Underbids ask for too little
money to complete the project. Cash flow problems exist when the present amount of funding cannot
cover the current costs for labour and materials, and because they are a matter of having sufficient
funds at a specific time, can arise even when the overall total is enough. Fraud is a problem in many
fields, but is notoriously prevalent in the construction field. Financial planning for the project is
intended to ensure that a solid plan, with adequate safeguards and contingency plans, is in place
before the project is started, and is required to ensure that the plan is properly executed over the life
of the project. Mortgage bankers, accountants, and cost engineers are likely participants in creating
an overall plan for the financial management of the building construction project. The presence of the
mortgage banker is highly likely even in relatively small projects, since the owner's equity in the
property is the most obvious source of funding for a building project. Accountants act to study the
expected monetary flow over the life of the project, and to monitor the payouts throughout the
process. Cost engineers apply expertise to relate the work and materials involved to a proper
valuation. Cost overruns with government projects have occurred when the contractor was able to
identify change orders or changes in the project resulting in large increases in cost, which are not
subject to competition by other firm as they have already been eliminated from consideration after the
initial bid.[1] Large projects can involve highly complex financial plans. As portions of a project are
completed, they may be sold, supplanting one lender or owner for another, while the logistical
requirements of having the right trades and materials available for each stage of the building
construction project carries forward. In many English speaking countries, but not the United States,
projects typically use quantity surveyors.
5
Legal considerations
A construction project must fit into the legal framework governing the property. These include
governmental regulations on the use of property, and obligations that are created in the process of
construction. The project must adhere to zoning and building code requirements. Constructing a
project that fails to adhere to codes will not benefit the owner. Some legal requirements come from
malum in se considerations, or the desire to prevent things that are indisputably bad - bridge
collapses or explosions. Other legal requirements come from malum prohibitum considerations, or
things that are a matter of custom or expectation, such as isolating businesses to a business district
and residences to a residential district. An attorney may seek changes or exemptions in the law
governing the land where the building will be built, either by arguing that a rule is inapplicable (the
bridge design won't collapse), or that the custom is no longer needed (acceptance of live-work spaces
has grown in the community). A construction project is a complex net of contracts and other legal
obligations, each of which must be carefully considered. A contract is the exchange of a set of
obligations between two or more parties, but it is not so simple a matter as trying to get the other
side to agree to as much as possible in exchange for as little as possible. The time element in
construction means that a delay costs money, and in cases of bottlenecks, the delay can be extremely
expensive. Thus, the contracts must be designed to ensure that each side is capable of performing the
obligations set out. Contracts that set out clear expectations and clear paths to accomplishing those
expectations are far more likely to result in the project flowing smoothly, whereas poorly drafted
contracts lead to confusion and collapse. Legal advisors in the beginning of a construction project seek
to identify ambiguities and other potential sources of trouble in the contract structure, and to present
options for preventing problems. Throughout the process of the project, they work to avoid and
resolve conflicts that arise. In each case, the lawyer facilitates an exchange of obligations that
matches the reality of the project.
Interaction of expertise
Design, finance, and legal aspects overlap and interrelate. The design must be not only structurally
sound and appropriate for the use and location, but must also be financially possible to build, and
legal to use. The financial structure must accommodate the need for building the design provided, and
must pay amounts that are legally owed. The legal structure must integrate the design into the
surrounding legal framework, and enforces the financial consequences of the construction process.
Procurement
Procurement describes the merging of activities undertaken by the client to obtain a building.
There are many different methods of construction procurement; however the three most common
types of procurement are:
1.
Traditional (Design-bid-build)
2.
Design and Build
3.
Management Contracting
Traditional
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This the most common method of construction procurement and is well established and recognized. In
this arrangement, the architect or engineer acts as the project coordinator. His or her role is to design
the works, prepare the specifications and produce construction drawings, administer the contract,
tender the works, and manage the works from inception to completion. There are direct contractual
links between the architect's client and the main contractor. Any subcontractor will have a direct
contractual relationship with the main contractor.
Design and build
This approach has become more common in recent years and includes an entire completed package,
including fixtures, fittings and equipment where necessary, to produce a completed fully functional
building. In some cases, the Design and Build (D & B) package can also include finding the site,
arranging funding and applying for all necessary statutory consents. The owner produces a list of
requirements for a project, giving an overall view of the project's goals. Several D&B contractors
present different ideas about how to accomplish these goals. The owner selects the ideas he likes best
and hires the appropriate contractor. Often, it is not just one contractor, but a consortium of several
contractors working together. Once a contractor (or a consortium/consortia) has been hired, they
begin building the first phase of the project. As they build phase 1, they design phase 2. This is in
contrast to a design-bid-build contract, where the project is completely designed by the owner, then
bid on, then completed. Kent Hansen, director of engineering for the National Asphalt Pavement
Association (NAPA), pointed out that state departments of transportation (DOTs) usually use design
build contracts as a way of getting projects done when states don't have the resources. In DOTs,
design build contracts are usually used for very large projects.
[2]
Management procurement systems
In this arrangement the client plays an active role in the procurement system by entering into
separate contracts with the designer (architect or engineer), the construction manager, and individual
trade contractors. The client takes on the contractual role, while the construction or project manager
provides the active role of managing the separate trade contracts, and ensuring that they all work
smoothly and effectively together. Management procurement systems are often used to speed up the
procurement processes, allow the client greater flexibility in design variation throughout the contract,
the ability to appoint individual work contractors, separate contractual responsibility on each individual
throughout the contract, and to provide greater client control. In construction, the authority having
jurisdiction (AHJ) is the governmental agency or sub-agency which regulates the construction
process. In most cases, this is the municipality in which the building is located. However, construction
performed for supra-municipal authorities are usually regulated directly by the owning authority,
which becomes the AHJ. During the planning of a building, the zoning and planning boards of the AHJ
will review the overall compliance of the proposed building with the municipal General Plan and zoning
regulations. Once the proposed building has been approved, detailed civil, architectural, and structural
plans must be submitted to the municipal building department (and sometimes the public works
department) to determine compliance with the building code and sometimes for fit with existing
7
infrastructure. Often, the municipal fire department will review the plans for compliance with firesafety ordinances and regulations.
Construction on a building in Kansas City
Before the foundation can be dug, contractors are typically required to notify utility companies, either
directly or through a company such as Dig Safe to ensure that underground utility lines can be
marked. This lessens the likelihood of damage to the existing electrical, water, sewage, phone, and
cable facilities, which could cause outages and potentially hazardous situations. During the
construction of a building, the municipal building inspector inspects the building periodically to ensure
that the construction adheres to the approved plans and the local building code. Once construction is
complete and a final inspection has been passed, an occupancy permit may be issued. An operating
building must remain in compliance with the fire code. The fire code is enforced by the local fire
department. Changes made to a building that affect safety, including its use, expansion, structural
integrity, and fire protection items, usually require approval of the AHJ for review concerning the
building code. There are many routes to the different careers within the construction industry which
vary by country.
Ironworkers erecting the steel frame of a new building, at the Massachusetts General Hospital, USA
However, there are three main tiers of careers based on educational background which are common
internationally:
Unskilled and Semi-Skilled - General site labour with little or no construction qualifications.
Skilled - On-site managers whom possess extensive knowledge and experience in their craft or
profession.
Technical and Management - Personnel with the greatest educational qualifications, usually
graduate degrees, trained to design, manage and instruct the construction process. Skilled
occupations in the UK require Further Education qualifications, often in vocational subject areas. These
qualifications are either obtained directly after the completion of compulsory education or through "on
the job" apprenticeship training. In the UK, 8500 construction-related apprenticeships were
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commenced in 2007.[3] Technical and specialised occupations require more training as a greater
technical knowledge is required. These professions also hold more legal responsibility. A short list of
the main careers with an outline of the educational requirements are given below:[4]
Architect - Typically holds at least a 4-year degree in architecture. To use the title "architect"
the individual must hold chartered status with the Royal Institute of British Architects and be on the
Architects Registration Board.
Civil Engineer - Typically holds a degree in a related subject. The Chartered Engineer
qualification is controlled by the Institution of Civil Engineers. A new university graduate must hold a
masters degree to become chartered, persons with bachelors degrees may become an Incorporated
Engineer.
Building Services Engineer - Often referred to as an "M&E Engineer" typically holds a degree in
mechanical or electrical engineering. Chartered Engineer status is governed by the Chartered
Institution of Building Services Engineers.
Project Manager - Typically holds a 2-year or greater higher education qualification, but are
often also qualified in another field such as quantity surveying or civil engineering.
Quantity Surveyor - Typically holds a masters degree in quantity surveying. Chartered status
is gained from the Royal Institute of Chartered Surveyors.
Structural Engineer - Typically holds a bachelors or masters degree in structural engineering,
new university graduates must hold a masters degree to gain chartered status from the Institution of
Structural Engineers.
PART II
Contents
1 Career
1.1 Work activities
1.2 Skills
1.3 Abilities
1.4 Educational requirements
2 See also
3 References
History
The first buildings were huts and shelters, constructed by hand or with simple tools. As cities grew
during the bronze age, a class of professional craftsmen like bricklayers and carpenters appeared.
Occasionally, slaves were used for construction work. In the middle ages, these were organized into
guilds. In the 19th century, steam-powered machinery appeared, and later diesel- and electric
powered vehicles such as cranes, excavators and bulldozers. Construction engineering concerns
the planning and management of the construction of structures such as highways, bridges, airports,
railroads, buildings, dams, and reservoirs. Construction of such projects requires knowledge of
engineering and management principles and business procedures, economics, and human behavior.
Construction engineers engage in the design of temporary structures, quality assurance and quality
9
control, building and site layout surveys, on site material testing, concrete mix design, cost
estimating, planning and scheduling, safety engineering, materials procurement, and cost engineering
and budgeting. Construction management is similar to construction engineering from the standpoint of
the level of mathematics, science and engineering used to analyze problems and design a construction
process.
Career
The construction industry in the United States provides employment to millions with all types and
levels of education. Construction contributes 14% of the United States Gross National Product.
Construction engineering provides much of the design aspect used both in the construction office and
in the field on project sites. To complete projects construction engineers rely on plans and
specifications created by architects, engineers and other constructors. During most of the 20th
century structures have been first designed then engineering staff ensure it is built to plans and
specifications by testing and overseeing the construction. Previous to the 20th century and more
commonly since the start of the 21st century structures are designed and built in combination,
allowing for site considerations and construction methods to influence the design process.
Work activities
Construction engineers have a wide range of responsibilities. Typically entry level construction
engineers analyze reports and estimate project costs both in the office and in the field. Other tasks
may include: Analyzing maps, drawings, blueprints, aerial photography and other topographical
information. Construction engineers also have to use computer software to design hydraulic systems
and structures while following construction codes. Keeping a workplace safe is key to having a
successful construction company. It is the construction engineer's job to make sure that everything is
conducted correctly. In addition to safety, the construction engineer has to make sure that the site
stays clean and sanitary. They have to make sure that there are no impediments in the way of the
structure's planned location and must move any that exist. Finally, more seasoned construction
engineers will assume the role of project management on a construction site and are involved heavily
with the construction schedule and document control as well as budget and cost control. Their role on
site is to provide construction information, including repairs, requests for information, change orders
and payment applications to the managers and/or the owner's representatives.
Skills
Construction engineers should have strong understanding for math and science, but many other skills
are required, including critical thinking, listening, learning, problem solving, monitoring and decision
making. Construction engineers have to be able to think about all aspects of a problem and listen to
other’s ideas so that they can learn everything about a project before it begins. During project
construction they must solve the problems that they encounter using math and science. Construction
Engineers must maintain project control of labor and equipment for safety, to ensure the project is on
schedule and monitor quality control. When a problem occurs it is the construction engineer who will
create and enact a solution.
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Abilities
Construction engineers need different abilities to do their job. They must have the ability to reason,
convey instructions to others, comprehend multi variables, anticipate problems, comprehend verbal,
written and graphic instructions, organize data sets, speak clearly, visualize in 4D time-space and
understand Virtual Design and Construction methods.
Educational requirements
A typical construction engineering curriculum is a mixture of engineering mechanics, engineering
design, construction management and general science and mathematics. This usually leads to a
Bachelor of Science degree. The B.S. degree along with some construction experience is sufficient for
most entry level construction engineering jobs. Graduate school may be an option for those who want
to go further in depth of the construction and engineering subjects taught at the undergraduate level.
In most cases construction engineering graduates look to either civil engineering, engineering
management, or business administration as a possible graduate degree. For authority to approve any
final designs of public projects (and most any project), a construction engineer must have a
professional engineers (P.E.) license. To obtain a P.E. license the Fundamentals of Engineering exam
and Principles and Practice in Engineering Exam must be passed and education and experience
requirements met. Architectural engineering, also known as Building Engineering, is the
application of engineering principles and technology to building design and construction. Definitions of
an architectural engineer may refer to:
An engineer in the structural, mechanical, electrical, construction or other engineering fields of
building design and construction.
A licensed engineering professional in parts of the United States, where architectural
engineering may include complete building design.[citation needed]
In informal contexts, and formally in some places, a professional synonymous with or similar
to an architect. In some languages, "architect" is literally translated as "architectural engineer".
11
THE THIRD TERM: PART III
Contents
1 Engineering for buildings
1.1 Structural
1.2 Mechanical, Electrical and Plumbing (MEP)
2 The Architectural engineer (PE) in the United States
3 The Architect as Architectural Engineer
4 Education
4.1 Architectural Engineering as a single integrated field of study
5 See also
6 References
Engineering for buildings
Structural
Structural engineering involves the analysis and design of physical objects such as buildings, bridges,
equipment supports, towers and walls. Those concentrating on buildings are responsible for the
structural performance of a large part of the built environment and are, sometimes, informally
referred to as "building engineers". Structural engineers require expertise in strength of materials and
in the seismic design of structures covered by earthquake engineering. Architectural Engineers
sometimes practice structural as one aspect of their designs; the structural discipline when practiced
as a specialty works closely with architects and other engineering specialists.
Mechanical, Electrical and Plumbing (MEP)
Some Architectural Engineers perform MEP for their own building designs; in most cases, however,
mechanical and electrical engineers are specialists, commonly referred to as "MEP" (mechanical,
electrical and plumbing) when engaged in the building design fields. Also known as "Building services
engineering" in the United Kingdom, Canada and Australia.[1] Mechanical engineers design and
oversee the heating ventilation and air conditioning (HVAC), plumbing, and rain gutter systems.
Plumbing designers often include design specifications for simple active fire protection systems, but
for more complicated projects, fire protection engineers are often separately retained. Electrical
engineers are responsible for the building's power distribution, telecommunication, fire alarm,
signalization, lightning protection and control systems, as well as lighting systems.
The Architectural engineer (PE) in the United States
In many jurisdictions of the United States, the architectural engineer is a licensed engineering
professional
[2],
usually a graduate of an architectural engineering university program preparing
students to perform whole-building design in competition with architect-engineer teams; or for
practice in one of structural, mechanical or electrical fields of building design, but with an appreciation
of integrated architectural requirements.
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Formal architectural engineering education, following the engineering model of earlier disciplines,
developed in the late 1800s, and became widespread in the United States by the mid 1900s. With the
establishment of a specific "architectural engineering" NCEES Professional Engineering registration
examination in the 1990s, and first offering in April 2003, architectural engineering became
recognized as a distinct engineering discipline in the United States. Architectural engineers are not
entitled to practice architecture unless they are also licensed as architects.
The Architect as Architectural Engineer
See also: Architect
In some countries architecture engineer, as a profession providing architectural services, is sometimes
referred to as "architectural engineering". In others, such as in Japan, the terms "architecture" and
"building engineering" are used synonymously.[3] The practice of architecture includes the planning,
designing and oversight of a building's construction. In some languages, such as Korean and Arabic,
"architect" is literally translated as "architectural engineer". In some countries, an "architectural
engineer" (such as the ingegnere edile in Italy) is entitled to practice architecture and is often referred
to as an architect.[4] These individuals are often also structural engineers. In other countries, such as
Germany and Austria, architecture graduates receive an engineering degree (Dip-Ing).[5]
Education
Further information: Engineer's degree
The architectural, structural, mechanical and electrical engineering branches each have well
established educational requirements that are usually fulfilled by completion of a university program.
Architectural Engineering as a single integrated field of study
What differentiates Architectural Engineering as a separate and single, integrated field of study,
compared to other engineering disciplines, is its multi-disciplined engineering approach. Through
training in and appreciation of architecture, the field seeks integration of building systems within its
overall building design. Architectural Engineering includes the design of building systems including
Heating, ventilation and air conditioning (HVAC), plumbing, fire protection, electrical, lighting,
transportation, and structural systems. In some university programs, students are required to
concentrate on one of the systems; in others, they can receive a generalist Architectural or Building
Engineering degree. The University of Sheffield, United Kingdom offers a Dual degree course in both
Architecture and Structural Engineering. Building officials of developed countries are generally
referred to as administering building control systems that are mostly defined in statute. According to
World Organisation of Building Officials, there were two distinct levels of building officials: (1) the
professionally-qualified building controls administrators, who are technically and/or professionally
competent in examining design documents for compliance with the Building Codes defined in statute;
and (2) the technician-level building-work inspectors, who simply administer the various processes.
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PART IV
Contents
1 Structural engineer
2 History of structural engineering
3 Significant structural failures and collapses
4 Specializations
5 Structural elements
6 Structural engineering theory
7 Materials
8 See also
9 References
10 Notes
11 External links
Structural engineer
Etymology
The term structural derives from the Latin word structus, which is "to
pile, build, assemble". The==Structural engineer==
Main article: Structural engineer
Etymology
The term structural derives from the Latin word structus, which is
"to pile, build, assemble". The first use of the term structure was
c.1440.[3] The term engineer derives from the old French term
engin, meaning "skill, cleverness" and also 'war machine'. This
term in turn derives from the Latin word ingenium, which means
"inborn qualities, talent", and is constructed of in- "in" + gen-, the
root of gignere, meaning "to beget, produce." The term engineer is
related to ingenious.[4]
The term structural engineer is generally applied to those who
have completed a degree in civil engineering specializing in the
design of structures, or a post-graduate degree in structural
engineering. However, an individual can become a structural
engineer through training and experience outside educational
14
institutions as well, perhaps most notably under the Institution of
Structural Engineers (UK) regulations. The training and experience
requirements
for
structural
engineers
varies
greatly,
being
governed in some way in most developed nations. In all cases the
term is regulated to restrict usage to only those individuals having
specialist knowledge of the requirements and design of safe,
serviceable, and economical structures.
The term engineer in isolation varies widely in its use and
application, and can, depending on the geographical location of its
use, refer to many different technical and creative professions in
its common usage.
Structural engineers are responsible for engineering design and analysis.
Entry-level structural engineers may design the individual structural
elements of a structure, for example the beams, columns, and floors of a
building. More experienced engineers would be responsible for the
structural design and integrity of an entire system, such as a building.
Structural engineers often specialise in particular fields, such as bridge
engineering,
building
engineering,
pipeline
engineering,
industrial
structures or special structures such as vehicles or aircraft.
Structural engineering has existed since humans first started to construct
their own structures. It became a more defined and formalised profession
with the emergence of the architecture profession as distinct from the
engineering profession during the industrial revolution in the late 19th
Century. Until then, the architect and the structural engineer were often
one and the same - the master builder. Only with the understanding of
structural theories that emerged during the 19th and 20th century did
the professional structural engineer come into existence.
The
role
of
a
structural
engineer
today
involves
a
significant
understanding of both static and dynamic loading, and the structures
that are available to resist them. The complexity of modern structures
often requires a great deal of creativity from the engineer in order to
ensure the structures support and resist the loads they are subjected to.
A structural engineer will typically have a four or five year undergraduate
degree, followed by a minimum of three years of professional practice
before being considered fully qualified.[5]
15
Structural engineers are licensed or accredited by different learned
societies and regulatory bodies around the world (for example, the
Institution of Structural Engineers in the UK)[5]. Depending on the degree
course they have studied and/or the jurisdiction they are seeking
licensure in, they may be accredited (or licensed) as just structural
engineers, or as civil engineers, or as both civil and structural engineers.
first use of the term structure was c.1440.[6] The term
engineer derives from the old French term engin, meaning
"skill, cleverness" and also 'war machine'. This term in turn
derives from the Latin word ingenium, which means "inborn
qualities, talent", and is constructed of in- "in" + gen-, the
root of gignere, meaning "to beget, produce." The term
engineer is related to ingenious.[7]
The term structural engineer is generally applied to those who have
completed a degree in civil engineering specializing in the design of
structures, or a post-graduate degree in structural engineering. However,
an individual can become a structural engineer through training and
experience outside educational institutions as well, perhaps most notably
under the Institution of Structural Engineers (UK) regulations. The
training and experience requirements for structural engineers varies
greatly, being governed in some way in most developed nations. In all
cases the term is regulated to restrict usage to only those individuals
having specialist knowledge of the requirements and design of safe,
serviceable, and economical structures.
The term engineer in isolation varies widely in its use and application,
and can, depending on the geographical location of its use, refer to many
different technical and creative professions in its common usage.
Structural engineers are responsible for engineering design and analysis. Entry-level structural
engineers may design the individual structural elements of a structure, for example the beams,
columns, and floors of a building. More experienced engineers would be responsible for the structural
design and integrity of an entire system, such as a building. Structural engineers often specialise in
particular fields, such as bridge engineering, building engineering, pipeline engineering, industrial
structures or special structures such as vehicles or aircraft. Structural engineering has existed since
humans first started to construct their own structures. It became a more defined and formalised
profession with the emergence of the architecture profession as distinct from the engineering
profession during the industrial revolution in the late 19th Century. Until then, the architect and the
structural engineer were often one and the same - the master builder. Only with the understanding of
structural theories that emerged during the 19th and 20th century did the professional structural
16
engineer come into existence. The role of a structural engineer today involves a significant
understanding of both static and dynamic loading, and the structures that are available to resist them.
The complexity of modern structures often requires a great deal of creativity from the engineer in
order to ensure the structures support and resist the loads they are subjected to. A structural
engineer will typically have a four or five year undergraduate degree, followed by a minimum of three
years of professional practice before being considered fully qualified. [5] Structural engineers are
licensed or accredited by different learned societies and regulatory bodies around the world (for
example, the Institution of Structural Engineers in the UK)[5]. Depending on the degree course they
have studied and/or the jurisdiction they are seeking licensure in, they may be accredited (or
licensed) as just structural engineers, or as civil engineers, or as both civil and structural engineers.
History of structural engineering
Statuette of Imhotep, in the Louvre, Paris, France
Structural engineering dates back to at least 2700 BC when the step pyramid for Pharaoh Djoser was
built by Imhotep, the first engineer in history known by name. Pyramids were the most common
major structures built by ancient civilisations because the structural form of a pyramid is inherently
stable and can be almost infinitely scaled (as opposed to most other structural forms, which cannot be
linearly increased in size in proportion to increased loads).[8] Throughout ancient and medieval history
most architectural design and construction was carried out by artisans, such as stone masons and
carpenters, rising to the role of master builder. No theory of structures existed, and understanding of
how structures stood up was extremely limited, and based almost entirely on empirical evidence of
'what had worked before'. Knowledge was retained by guilds and seldom supplanted by advances.
Structures were repetitive, and increases in scale were incremental. [8] No record exists of the first
calculations of the strength of structural members or the behaviour of structural material, but the
profession of structural engineer only really took shape with the industrial revolution and the reinvention of concrete (see History of concrete). The physical sciences underlying structural
engineering began to be understood in the Renaissance and have been developing ever since.
Specializations
Building structures
17
Sydney Opera House, designed by Ove Arup & Partners, with the architect Jorn Utzon
Millennium Dome in London, UK, by Buro Happold and Richard Rogers
Structural building engineering includes all structural engineering related to the design of buildings. It
is the branch of structural engineering that is close to architecture. Structural building engineering is
primarily driven by the creative manipulation of materials and forms and the underlying mathematical
and scientific principles to achieve an end which fulfills its functional requirements and is structurally
safe when subjected to all the loads it could reasonably be expected to experience, while being
economical and practical to construct. This is subtly different to architectural design, which is driven
by the creative manipulation of materials and forms, mass, space, volume, texture and light to
achieve an end which is aesthetic, functional and often artistic. The architect is usually the lead
designer on buildings, with a structural engineer employed as a sub-consultant. The degree to which
each discipline actually leads the design depends heavily on the type of structure. Many structures are
structurally simple and led by architecture, such as multi-storey office buildings and housing, while
other structures, such as tensile structures, shells and gridshells are heavily dependent on their form
for their strength, and the engineer may have a more significant influence on the form, and hence
much of the aesthetic, than the architect. Between these two extremes, structures such as stadia,
museums and skyscrapers are complex both architecturally and structurally, and a successful design is
a collaboration of equals. The structural design for a building must ensure that the building is able to
stand up safely, able to function without excessive deflections or movements which may cause fatigue
of structural elements, cracking or failure of fixtures, fittings or partitions, or discomfort for occupants.
It must account for movements and forces due to temperature, creep, cracking and imposed loads. It
must also ensure that the design is practically buildable within acceptable manufacturing tolerances of
the materials. It must allow the architecture to work, and the building services to fit within the
building and function (air conditioning, ventilation, smoke extract, electrics, lighting etc). The
structural design of a modern building can be extremely complex, and often requires a large team to
complete. Structural engineering specialties for buildings include:
Earthquake engineering
Façade engineering
Fire engineering
Roof engineering
Tower engineering
18
Wind engineering
Earthquake engineering structures
Main article: Earthquake engineering
Earthquake engineering structures are those engineered to withstand various types of hazardous
earthquake exposures at the sites of their particular location.
Earthquake-proof and massive pyramid El Castillo, Chichen Itza
Earthquake engineering is treating its subject structures like defensive fortifications in military
engineering but for the warfare on earthquakes. Both earthquake and military general design
principles are similar: be ready to slow down or mitigate the advance of a possible attacker.
The main objectives of earthquake engineering are:
Snapshot from shake-table video [1] of testing base-isolated (right) and
regular (left) building model
Understand interaction of structures with the shaky ground.
Foresee the consequences of possible earthquakes.
Design, construct and maintain structures to perform at
earthquake exposure up to the expectations and in compliance with
building codes.
Earthquake engineering or earthquake-proof
structure does not, necessarily, means extremely strong and expensive one like El Castillo pyramid
at Chichen Itza shown above. Now, the most powerful and budgetary tool of the earthquake
engineering is base isolation which pertains to the passive structural vibration control technologies.
Civil engineering structures
The Millau Viaduct in France, designed by Michel Virlogeux with Foster & Partners
The structural engineer is the lead designer on these structures, and often the sole
designer. In the design of structures such as these, structural safety is of
paramount importance (in the UK, designs for dams, nuclear power stations and
bridges must be signed off by a chartered engineer). Civil engineering structures are often subjected
to very extreme forces, such as large variations in temperature, dynamic loads such as waves or
traffic, or high pressures from water or compressed gases.
Civil structural engineering includes all structural engineering related to the built environment. It
includes:
Bridges
Dams
Earthworks
Foundations
Power stations
Railways
Retaining structures and walls
Roads
19
Offshore structures
Pipelines
Tunnels
Waterways
They are also often constructed in corrosive environments, such as at sea, in industrial facilities or
below ground.
THE FOURTH TERM: Mechanical structures
An Airbus A380, the world's largest passenger airliner
The design of static structures assumes they always have the same geometry (in fact, so-called static
structures can move significantly, and structural engineering design must take this into account where
necessary), but the design of moveable or moving structures must account for fatigue, variation in the
method in which load is resisted and significant deflections of structures. The forces which parts of a
machine are subjected to can vary significantly, and can do so at a great rate. The forces which a boat
or aircraft are subjected to vary enormously and will do so thousands of times over the structure's
lifetime. The structural design must ensure that such structures are able to endure such loading for
their entire design life without failing. These works can require mechanical structural engineering:
Airframes and fuselages
Boilers and pressure vessels
Coachworks and carriages
Cranes
Elevators
Escalators
Marine vessels and hulls
Structural elements
A statically determinate simply supported beam, bending under an evenly distributed load.
Any structure is essentially made up of only a small number of different types of elements:
Columns
Beams
Plates
Arches
Shells
Catenaries
Many of these elements can be classified according to form (straight, plane / curve) and
dimensionality (one-dimensional / two-dimensional):
One-dimensional
20
Two-dimensional
straight
(predominantly) bending
beam
(predominant) tensile stress
rope
(predominant) compression
curve
plane
curve
continuous arch plate, concrete slab lamina, dome
Catenary
pier, column
shell
Load-bearing wall
Columns
Columns are elements that carry only axial force - either tension or compression - or both axial force
and bending (which is technically called a beam-column but practically, just a column). The design of
a column must check the axial capacity of the element, and the buckling capacity. The buckling
capacity is the capacity of the element to withstand the propensity to buckle. Its capacity depends
upon its geometry, material, and the effective length of the column, which depends upon the restraint
conditions at the top and bottom of the column. The effective length is K * l where l is the real length
of the column. The capacity of a column to carry axial load depends on the degree of bending it is
subjected to, and vice versa. This is represented on an interaction chart and is a complex non-linear
relationship.
Beams
A beam may be:
cantilevered (supported at one end only with a fixed connection)
simply supported (supported vertically at each end; horizontally on only one to withstand
friction, and able to rotate at the supports)
continuous (supported by three or more supports)
a combination of the above (ex. supported at one end and in the middle)
Beams are elements which carry pure bending only. Bending causes one section of a beam (divided
along its length) to go into compression and the other section into tension. The compression section
must be designed to resist buckling and crushing, while the tension section must be able to
adequately resist the tension.
Struts and ties
Little Belt: a truss bridge in Denmark
21
The McDonnell Planetarium by Gyo Obata in St Louis, Missouri, USA, a concrete shell structure
A masonry arch
1. Keystone 2. Voussoir 3. Extrados 4. Impost 5. Intrados 6. Rise 7. Clear span
8. Abutment
A truss is a structure comprising two types of structural element, ie struts and
ties. A strut is a relatively lightweight column and a tie is a slender element
designed to withstand tension forces. In a pin-jointed truss (where all joints are
essentially hinges), the individual elements of a truss theoretically carry only axial load. From
experiments it can be shown that even trusses with rigid joints will behave as though the joints are
pinned.Trusses are usually utilised to span large distances, where it would be uneconomical and
unattractive to use solid beams.
Plates
Plates carry bending in two directions. A concrete flat slab is an example of a plate. Plates are
understood by using continuum mechanics, but due to the complexity involved they are most often
designed using a codified empirical approach, or computer analysis. They can also be designed with
yield line theory, where an assumed collapse mechanism is analysed to give an upper bound on the
collapse load (see Plasticity). This is rarely used in practice.
Shells
Shells derive their strength from their form, and carry forces in compression in two directions. A dome
is an example of a shell. They can be designed by making a hanging-chain model, which will act as a
catenary in pure tension, and inverting the form to achieve pure compression.
Arches
Arches carry forces in compression in one direction only, which is why it is appropriate to build arches
out of masonry. They are designed by ensuring that the line of thrust of the force remains within the
depth of the arch.
Catenaries
Catenaries derive their strength from their form, and carry transverse forces in pure tension by
deflecting (just as a tightrope will sag when someone walks on it). They are almost always cable or
fabric structures. A fabric structure acts as a catenary in two directions.
Structural engineering theory
22
Figure of a bolt in shear. Top figure illustrates single shear, bottom figure illustrates double shear.
Structural engineering depends upon a detailed knowledge of loads, physics and materials to
understand and predict how structures support and resist self-weight and imposed loads. To apply the
knowledge successfully a structural engineer will need a detailed knowledge of mathematics and of
relevant empirical and theoretical design codes. He will also need to know about the corrosion
resistance of the materials and structures, especially when those structures are exposed to the
external environment. The criteria which govern the design of a structure are either serviceability
(criteria which define whether the structure is able to adequately fulfill its function) or strength
(criteria which define whether a structure is able to safely support and resist its design loads). A
structural engineer designs a structure to have sufficient strength and stiffness to meet these criteria.
Loads imposed on structures are supported by means of forces transmitted through structural
elements. These forces can manifest themselves as:
tension (axial force)
compression (axial force)
shear
bending, or flexure (a bending moment is a force multiplied by a distance, or lever arm, hence
producing a turning effect or torque)
Loads
Some Structural loads on structures can be classified as live (imposed) loads, dead loads, earthquake
(seismic) loads, wind loads, soil pressure loads, fluid pressure loads, impact loads, and vibratory
loads. Live loads are transitory or temporary loads, and are relatively unpredictable in magnitude.
They may include the weight of a building's occupants and furniture, and temporary loads the
structure is subjected to during construction. Dead loads are permanent, and may include the weight
of the structure itself and all major permanent components. Dead load may also include the weight of
the structure itself supported in a way it wouldn't normally be supported, for example during
construction.
Strength
Strength depends upon material properties. The strength of a material depends on its capacity to
withstand axial stress, shear stress, bending, and torsion. The strength of a material is measured in
force per unit area (newtons per square millimetre or N/mm², or the equivalent megapascals or MPa
23
in the SI system and often pounds per square inch psi in the United States Customary Units system).
A structure fails the strength criterion when the stress (force divided by area of material) induced by
the loading is greater than the capacity of the structural material to resist the load without breaking,
or when the strain (percentage extension) is so great that the element no longer fulfills its function
(yield).
Stiffness
Stiffness depends upon material properties and geometry. The stiffness of a structural element of a
given material is the product of the material's Young's modulus and the element's second moment of
area. Stiffness is measured in force per unit length (newtons per millimetre or N/mm), and is
equivalent to the 'force constant' in Hooke's Law. The deflection of a structure under loading is
dependent on its stiffness. The dynamic response of a structure to dynamic loads (the natural
frequency of a structure) is also dependent on its stiffness. In a structure made up of multiple
structural elements where the surface distributing the forces to the elements is rigid, the elements will
carry loads in proportion to their relative stiffness - the stiffer an element, the more load it will attract.
In a structure where the surface distributing the forces to the elements is flexible (like a wood framed
structure), the elements will carry loads in proportion to their relative tributary areas. A structure is
considered to fail the chosen serviceability criteria if it is insufficiently stiff to have acceptably small
deflection or dynamic response under loading. The inverse of stiffness is the flexibility.
See also: Flexibility method and Direct stiffness method
Safety factors
The safe design of structures requires a design approach which takes account of the statistical
likelihood of the failure of the structure. Structural design codes are based upon the assumption that
both the loads and the material strengths vary with a normal distribution. The job of the structural
engineer is to ensure that the chance of overlap between the distribution of loads on a structure and
the distribution of material strength of a structure is acceptably small (it is impossible to reduce that
chance to zero). It is normal to apply a partial safety factor to the loads and to the material strengths,
to design using 95th percentiles (two standard deviations from the mean). The safety factor applied to
the load will typically ensure that in 95% of times the actual load will be smaller than the design load,
while the factor applied to the strength ensures that 95% of times the actual strength will be higher
than the design strength. The safety factors for material strength vary depending on the material and
the use it is being put to and on the design codes applicable in the country or region.
Load cases
A load case is a combination of different types of loads with safety factors applied to them. A
structure is checked for strength and serviceability against all the load cases it is likely to experience
during its lifetime.
Typical load cases for design for strength (ultimate load cases; ULS) are:
1.4 x Dead Load + 1.6 x Live Load
24
1.2 x Dead Load + 1.2 x Live Load + 1.2 x Wind Load
A typical load case for design for serviceability (characteristic load cases; SLS) is:
1.0 x Dead Load + 1.0 x Live Load
Different load cases would be used for different loading conditions. For example, in the case of design
for fire a load case of 1.0 x Dead Load + 0.8 x Live Load may be used, as it is reasonable to assume
everyone has left the building if there is a fire.
In multi-story buildings it is normal to reduce the total live load depending on the number of stories
being supported, as the probability of maximum load being applied to all floors simultaneously is
negligibly small.
It is not uncommon for large buildings to require hundreds of different load cases to be considered in
the design.
Newton's laws of motion
The most important natural laws for structural engineering are Newton's Laws of Motion. Newton's first
law states that every body perseveres in its state of being at rest or of moving uniformly straight
forward, except insofar as it is compelled to change its state by force impressed. Newton's second law
states that the rate of change of momentum of a body is proportional to the resultant force acting on
the body and is in the same direction. Mathematically, F=ma (force = mass x acceleration). Newton's
third law states that all forces occur in pairs, and these two forces are equal in magnitude and
opposite in direction. With these laws it is possible to understand the forces on a structure and how
that structure will resist them. The Third Law requires that for a structure to be stable all the internal
and external forces must be in equilibrium. This means that the sum of all internal and external forces
on a free-body diagram must be zero:
: the vectorial sum of the forces acting on the body equals zero. This translates to
Σ H = 0: the sum of the horizontal components of the forces equals zero;
Σ V = 0: the sum of the vertical components of forces equals zero;
: the sum of the moments (about an arbitrary point) of all forces equals zero.
Statical determinacy
A structural engineer must understand the internal and external forces of a structural system
consisting of structural elements and nodes at their intersections. A statically determinate structure
can be fully analysed using only consideration of equilibrium, from Newton's Laws of Motion. A
statically indeterminate structure has more unknowns than equilibrium considerations can supply
equations for (see simultaneous equations). Such a system can be solved using consideration of
equations of compatibility between geometry and deflections in addition to equilibrium equations, or
by using virtual work.
If a system is made up of b bars, j pin joints and r support reactions, then it cannot be statically
determinate if the following relationship does not hold:
25
r + b = 2j
It should be noted that even if this relationship does hold, a structure can be arranged in such a way
as to be statically indeterminate.[26]
Elasticity
See also: Hooke's Law
Much engineering design is based on the assumption that materials behave elastically. For most
materials this assumption is incorrect, but empirical evidence has shown that design using this
assumption can be safe. Materials that are elastic obey Hooke's Law, and plasticity does not occur.
For systems that obey Hooke's Law, the extension produced is directly proportional to the load:
where
x is the distance that the spring has been stretched or compressed away from the equilibrium
position, which is the position where the spring would naturally come to rest [usually in meters],
F is the restoring force exerted by the material [usually in newtons], and k is the force constant (or
spring constant). This is the stiffness of the spring. The constant has units of force per unit length
(usually in newtons per metre)
Plasticity
Comparison of Tresca and Von Mises Criteria
Some design is based on the assumption that materials will behave plastically.[27] A plastic material is
one which does not obey Hooke's Law, and therefore deformation is not proportional to the applied
load. Plastic materials are ductile materials. Plasticity theory can be used for some reinforced concrete
structures assuming they are underreinforced, meaning that the steel reinforcement fails before the
concrete does.
Plasticity theory states that the point at which a structure collapses (reaches yield) lies between an
upper and a lower bound on the load, defined as follows:
26
If, for a given external load, it is possible to find a distribution of moments that satisfies
equilibrium requirements, with the moment not exceeding the yield moment at any location, and if the
boundary conditions are satisfied, then the given load is a lower bound on the collapse load.
If, for a small increment of displacement, the internal work done by the structure, assuming
that the moment at every plastic hinge is equal to the yield moment and that the boundary conditions
are satisfied, is equal to the external work done by the given load for that same small increment of
displacement, then that load is an upper bound on the collapse load.
If the correct collapse load is found, the two methods will give the same result for the collapse load. [28]
Plasticity theory depends upon a correct understanding of when yield will occur. A number of different
models for stress distribution and approximations to the yield surface of plastic materials exist:[29]
Mohr's circle
Von Mises yield criterion
Henri Tresca
The Euler-Bernoulli beam equation
The Euler-Bernoulli beam equation defines the behaviour of a beam element (see below). It is based
on five assumptions:
(1) continuum mechanics is valid for a bending beam
(2) the stress at a cross section varies linearly in the direction of bending, and is zero at the centroid
of every cross section.
(3) the bending moment at a particular cross section varies linearly with the second derivative of the
deflected shape at that location.
(4) the beam is composed of an isotropic material
(5) the applied load is orthogonal to the beam's neutral axis and acts in a unique plane.
A simplified version of Euler-Bernoulli beam equation is:
Here u is the deflection and w(x) is a load per unit length. E is the elastic modulus and I is the second
moment of area, the product of these giving the stiffness of the beam.
This equation is very common in engineering practice: it describes the deflection of a uniform, static
beam.
Successive derivatives of u have important meaning:
is the deflection.
is the slope of the beam.
is the bending moment in the beam.
is the shear force in the beam.
27
A bending moment manifests itself as a tension and a compression force, acting as a couple in a
beam. The stresses caused by these forces can be represented by:
where σ is the stress, M is the bending moment, y is the distance from the neutral axis of the beam to
the point under consideration and I is the second moment of area. Often the equation is simplified to
the moment divided by the section modulus (S), which is I/y. This equation allows a structural
engineer to assess the stress in a structural element when subjected to a bending moment.
Buckling
A column under a centric axial load exhibiting the characteristic deformation
of buckling.
Lateral-torsional buckling of an aluminium alloy plate girder designed and built by students at Imperial College
London.
When subjected to compressive forces it is possible for structural elements to deform significantly due
to the destabilising effect of that load. The effect can be initiated or exacerbated by possible
inaccuracies in manufacture or construction.
The Euler buckling formula defines the axial compression force which will cause a strut (or column) to
fail in buckling.
where
F = maximum or critical force (vertical load on column),
E = modulus of elasticity,
I = area moment of inertia, or second moment of area
l = unsupported length of column,
K = column effective length factor, whose value depends on the conditions of end support of the
column, as follows.
For both ends pinned (hinged, free to rotate), K = 1.0.
For both ends fixed, K = 0.50.
28
For one end fixed and the other end pinned,
0.70.
For one end fixed and the other end free to move laterally, K = 2.0.
This value is sometimes expressed for design purposes as a critical buckling stress.
where
σ = maximum or critical stress
r = the least radius of gyration of the cross section
Other forms of buckling include lateral torsional buckling, where the compression flange of a beam in
bending will buckle, and buckling of plate elements in plate girders due to compression in the plane of
the plate.
Materials
Stress-strain curve for low-carbon steel. Hooke's law (see above) is only valid for the portion of the curve
between the origin and the yield point.
1. Ultimate strength
2. Yield strength-corresponds to yield point.
3. Rupture
4. Strain hardening region
5. Necking region.
A: Apparent stress (F/A0)
B: Actual stress (F/A)
Structural engineering depends on the knowledge of materials and their properties, in order to
understand how different materials support and resist loads.
Common structural materials are:
Iron
Wrought iron
Wrought iron is the simplest form of iron, and is almost pure iron (typically less than 0.15% carbon).
It usually contains some slag. Its uses are almost entirely obsolete, and it is no longer commercially
produced. Wrought iron is very poor in fires. It is ductile, malleable and tough. It does not corrode as
easily as steel.
Cast iron
29
Cast iron is a brittle form of iron which is weaker in tension than in compression. It has a relatively
low melting point, good fluidity, castability, excellent machinability and wear resistance. Though
almost entirely replaced by steel in building structures, cast irons have become an engineering
material with a wide range of applications, including pipes, machine and car parts. Cast iron retains
high strength in fires, despite its low melting point. It is usually around 95% iron, with between 2.14% carbon and between 1-3% silicon. It does not corrode as easily as
steel.
Steel
The 630 foot (192 m) high, stainless-clad (type 304) Gateway Arch in Saint
Louis, Missouri
See also: Steel frame
Steel is a iron alloy with between 0.2 and 1.7% carbon. Steel is used
extremely widely in all types of structures, due to its relatively low cost,
high strength to weight ratio and speed of construction. Steel is a ductile
material, which will behave elastically until it reaches yield (point 2 on
the stress-strain curve), when it becomes plastic and will fail in a ductile manner (large strains, or
extensions, before fracture at point 3 on the curve). Steel is equally strong in tension and
compression. Steel is weak in fires, and must be protected in most buildings. Because of its high
strength to weight ratio, steel buildings typically have low thermal mass, and require more energy to
heat (or cool) than similar concrete buildings. The elastic modulus of steel is approximately 205 GPa.
Steel is very prone to corrosion (rust).
Stainless steel
Stainless steel is an iron-carbon alloy with a minimum of 10.5% chromium content. There are
different types of stainless steel, containing different proportions of iron, carbon, molybdenum, nickel.
It has similar structural properties to steel, although its strength varies significantly. It is rarely used
for primary structure, and more for architectural finishes and building cladding. It is highly resistant to
corrosion and staining.
Concrete
Concrete is used extremely widely in building and civil engineering structures, due to its low cost,
flexibility, durability, and high strength. It also has high resistance to fire. Concrete is a brittle
material and it is strong in compression and very weak in tension.
The interior of the Sagrada Familia, constructed of reinforced concrete to a design by Gaudi
30
A "cage" of reinforcing steel
It behaves non-linearly at all times. Because it has essentially zero strength in tension, it is almost
always used as reinforced concrete, a composite material. It is a mixture of sand, aggregate, cement
and water. It is placed in a mould, or form, as a liquid, and then it sets (goes off), due to a chemical
reaction between the water and cement. The hardening of the concrete is called curing. The reaction is
exothermic (gives off heat). Concrete increases in strength continually from the day it is cast.
Assuming it is not cast under water or in constantly 100% relative humididy, it shrinks over time as it
dries out, and it deforms over time due to a phenomenon called creep. Its strength depends highly on
how it is mixed, poured, cast, compacted, cured (kept wet while setting), and whether or not any
admixtures were used in the mix. It can be cast into any shape that a form can be made for. Its
colour, quality, and finish depend upon the complexity of the structure, the material used for the form,
and the skill of the worker.Concrete is a non-linear, non-elastic material, and will fail suddenly, with a
brittle failure, unless adequate reinforced with steel. An "under-reinforced" concrete element will fail
with a ductile manner, as the steel will fail before the concrete. An "over-reinforced" element will fail
suddenly, as the concrete will fail first. Reinforced concrete elements should be designed to be underreinforced so users of the structure will receive warning of impending collapse. This is a technical
term. Reinforced concrete can be designed without enough reinforcing. A better term would be
properly reinforced where the member can resist all the design loads adequately and it is not overreinforced. The elastic modulus of concrete can vary widely and depends on the concrete mix, age,
and quality, as well as on the type and duration of loading applied to it. It is usually taken as
approximately 25 GPa for long-term loads once it has attained its full strength (usually considered to
be at 28 days after casting). It is taken as approximately 38 GPa for very short-term loading, such as
footfalls. Concrete has very favourable properties in fire - it is not adversely affected by fire until it
reaches very high temperatures. It also has very high mass, so it is good for providing sound
insulation and heat retention (leading to lower energy requirements for the heating of concrete
buildings). This is offset by the fact that producing and transporting concrete is very energy intensive.
Aluminium
31
Stress vs. Strain curve typical of aluminum
1. Ultimate strength
2. Yield strength
3. Proportional Limit Stress
4. Rupture
5. Offset strain (typically 0.002).
Aluminium is a soft, lightweight, malleable metal. The yield strength of pure aluminium is 7–11 MPa,
while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has about
one-third the density and stiffness of steel. It is ductile, and easily machined, cast, and extruded.
Corrosion resistance is excellent due to a thin surface layer of aluminium oxide that forms when the
metal is exposed to air, effectively preventing further oxidation. The strongest aluminium alloys are
less corrosion resistant due to galvanic reactions with alloyed copper. Aluminium is used in some
building structures (mainly in facades) and very widely in aircraft engineering because of its good
strength to weight ratio. It is a relatively expensive material. In aircraft it is gradually being replaced
by carbon composite materials.
Composites
Light composite aircraft
Composite materials are used increasingly in vehicles and aircraft structures, and to some extent in
other structures. They are increasingly used in bridges, especially for conservation of old structures
such as Coalport cast iron bridge built in 1818. Composites are often anisotropic (they have different
material properties in different directions) as they can be laminar materials. They most often behave
non-linearly and will fail in a brittle manner when overloaded. They provide extremely good strength
to weight ratios, but are also very expensive. The manufacturing processes, which are often extrusion,
do not currently provide the economical flexibility that concrete or steel provide. The most commonly
used in structural applications are glass-reinforced plastics.
Masonry
32
A brick wall built using Flemish Bond
Masonry has been used in structures for hundreds of years, and can take the form of stone, brick or
blockwork. Masonry is very strong in compression but cannot carry tension (because the mortar
between bricks or blocks is unable to carry tension). Because it cannot carry structural tension, it also
cannot carry bending, so masonry walls become unstable at relatively small heights. High masonry
structures require stabilisation against lateral loads from buttresses (as with the flying buttresses seen
in many European medieval churches) or from windposts. Historically masonry was constructed with
no mortar or with lime mortar. In modern times cement based mortars are used. The mortar glues the
blocks together, and also smoothes out the interface between the blocks, avoiding localised point
loads that might have led to cracking. Since the widespread use of concrete, stone is rarely used as a
primary structural material, often only appearing as a cladding, because of its cost and the high skills
needed to produce it. Brick and concrete blockwork have taken its place. Masonry, like concrete, has
good sound insulation properties and high thermal mass, but is generally less energy intensive to
produce. It is just as energy intensive as concrete to transport.
Timber
The reconstructed Globe Theatre, London, by Buro Happold
Timber is the oldest of structural materials, and though mainly supplanted by steel, masonry and
concrete, it is still used in a significant number of buildings. The properties of timber are non-linear
and very variable, depending on the quality, treatment of wood, and type of wood supplied. The
design of wooden structures is based strongly on empirical evidence. Wood is strong in tension and
compression, but can be weak in bending due to its fibrous structure. Wood is relatively good in fire as
it chars, which provides the wood in the centre of the element with some protection and allows the
structure to retain some strength for a reasonable length of time.
Other structural materials
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Bamboo scaffolding can reach great heights.
Adobe
Bamboo
Mud bricks
Roofing materials
PART V
Contents
1 New Zealand
2 United States
3 England & Wales
4 Notes
5 See also
6 External links
New Zealand
The government of New Zealand has set up a mediation service
[1]
to resolve cases of houses that
failed watertightness.
United States
In the United States, there were three major nonprofit organizations developing building codes for the
governing of building constructions, but they have since been merged into one in 1994, the
International Code Council (ICC). ICC publishes the International Building Codes, used by most of the
jurisdictions within the United States. The former organizations included Building Officials and Code
Administrators International, Inc. (BOCA), International Conference of Building Officials (ICBO), and
Southern Building Code Congress International, Inc. (SBCCI).
England & Wales
In England and Wales building control bodies (BCB) may be of two primary forms, either established
under Local Authority control or private bodies (Approved Inspectors). Applicants wishing to carry out
work controlled under the Building Act have the choice to select either the local Building Control or an
Approved Inspector. However, where local legislation is prevalent the Approved Inspector will be
charged with liaising with the relevant local authority body for the necessary approvals.
The Secretary of State issues guidance in support of the Building Regulations in the form of Approved
Documents which are not mandatory. The Building Regulations are functional and therefore designers
are free to offer alternative solutions to satisfying the the functional requirements. The burden of
proof is then placed on the designers to demonstrate that the alternative solution proposed offers a
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level of performance which satisfies the intent of the functional requirement. There is nothing in the
Regulations which imposes a duty on the applicant under those circumstances to use the guidance as
a benchmark of performance, although this is of course a route often taken as a way of demonstrating
that an alternative approach is of an acceptable standard. Appeals against decisions made by BCBs
are to the Secretary of State who will make a determination after considering all of the facts of a
particular case. Structural engineering is a field of engineering dealing with the analysis and design
of structures that support or resist loads. Structural engineering is usually considered a specialty
within civil engineering, but it can also be studied in its own right.[1] Structural engineers are most
commonly involved in the design of buildings and large nonbuilding structures[2] but they can also be
involved in the design of machinery, medical equipment, vehicles or any item where structural
integrity affects the item's function or safety. Structural engineers must ensure their designs satisfy
given design criteria, predicated on safety (e.g. structures must not collapse without due warning) or
serviceability and performance (e.g. building sway must not cause discomfort to the occupants).
Structural engineering theory is based upon physical laws and empirical knowledge of the structural
performance of different geometries and materials. Structural engineering design utilises a relatively
small number of basic structural elements to build up structural systems than can be very complex.
Structural engineers are responsible for making creative and efficient use of funds, structural elements
and materials to achieve these goals.[2]
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