Download Canterbury Earthquakes – Impact on the Ministry

Ministry of Education
Canterbury
Earthquakes
Impact on the Ministry of
Education’s School Buildings
Ministry of Education
Canterbury
Earthquakes
Impact on the Ministry of Education’s
School Buildings
Prepared By
Toby Tscherry
Structural Engineer
Reviewed By
Will Parker
Technical Principal – Earthquake Engineering &
Building Structures
© Opus International Consultants Ltd 2015
Opus International Consultants Ltd
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PO Box 1482, Christchurch Mail Centre,
Christchurch 8140
New Zealand
Telephone:
Facsimile:
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Date:
Reference:
Status:
16 January 2015
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
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Executive Summary
This report has been written for the Ministry of Education (“the Ministry” or MoE). The purpose of
this report is to review performance of school buildings in the Canterbury earthquake sequence.
The intent is to assist the Ministry of Education in improving the resilience of their current and
future school buildings in Christchurch and throughout New Zealand.
The post-earthquake review sampled 70 school buildings in Canterbury classified into 25 types.
The majority of school buildings reviewed are single storey, with the remainder being a maximum
of 2 storeys.
Buildings selected range in age from the 1930s through to 1990s. The buildings have been chosen
to be representative of school blocks throughout New Zealand, thus the majority of the sample
captures buildings from the 1950s through to the 1970s, when ‘standard’ designs were used
nationally (or regionally). After this period, one-off designs prepared by local architects seem to
dominate the building stock. It was not attempted to capture these newer designs in the sample,
because the lessons from these one-off designs have less relevance to the national portfolio.
Conclusions drawn about safety emphasize that there were no fatalities on school sites although
some injuries occurred, mostly resulting during egress. The Ministry’s earthquake strengthening
programme has been effective; it prevented building collapse, provided a safe environment for
teachers and students and limited damage to buildings that would otherwise have been more
severely affected. A significant conclusion is that a large proportion of damage was the result of
ground deformation. A key recommendation is that the Ministry consider this and other site
related risks nationally.
Conclusions on structural performance are:
 Lightweight wall and roof timber buildings have performed very well generally and in excess of
their calculated capacity.
 Seismic retrofit work undertaken has been effective.
 A large proportion of building damage was due to ground deformation.
 Lightweight buildings with suspended timber floors on shallow footings generally
accommodate ground deformation well and can often be quickly and cost effectively re-levelled.
 Overhead heavy building services or items unsecured on shelves can be a falling hazard.
 Most heavy roofs have been removed and replaced with lightweight material, which has
reduced the seismic load and damage.
 Where blocks have been joined together and the alignment of the principle axes are no longer
maintained such that the footprint is not symmetrical, i.e. joined together to form a T shaped
footprint, increased damage was observed.
 Heavy veneer cladding increases damage to internal linings.
 Overhead heavy veneer can be a falling hazard if not well tied to timber framing, particularly
above doors and windows.
 The open plan blocks have minimal bracing which increases frame distortion and damage.
 Some CEBUS type buildings have external nail plates that have failed during shaking without
resulting in collapse. These can be simply retrofitted.
 One of the Pre-1930’s Two Storey Block’s has Potential Critical Structural Weaknesses while up
to 11 others have structural weaknesses.
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Site Considerations – Recommendations Buildings and Infrastructure
 An egress and evacuation plan should be put in place for each school site. The main issues are
concerning stuck doors due to differential settlement and potential fall hazards. The assembly
point should also be considered.
 Overhead falling hazards relating to poorly tied brick veneer, heavy building services or items
on shelving should be assessed, and if required secured or removed to a lower height.
 Consideration should be given to assessing and, if required, strengthening, or removing the
veneer at height to mitigate this risk in a future significant earthquake event. Lowering the
veneer will have the added benefit of reducing the seismic load on the buildings’ structure and
improving its overall performance.
 Consideration should be given to upgrading site infrastructure during significant
developments. This would reduce the extent of aged, frequently extended, brittle pipe networks
present on many school sites.
 Consideration should be given to the assessment of schools’ existing infrastructure networks,
for their condition and capacity i.e. compliance and vulnerability. This would indicate a need
for the upgrade of any existing infrastructure with newer, more robust systems. This also
reduces the risk of major costs associated with repairing older systems, when repairs carried
out in the future might trigger the requirement for a Building Consent. Discussion with
Councils should also be considered to seek clarity on compliance requirements.
 Consideration should be given to contingency measures for lifeline services (water supply &
sewer).
 Consider options for hardstands that include ‘full design life’ to mitigate known geotechnical
risks.
Process – Recommendations and further review
 Issue minimum standard brief and guidelines for engineering assessment and design which
embodies current ‘best practice’. (We note that the Ministry have subsequently issued
guidelines on importance level for retrofit and new design).
 Consider adopting damage resistant designs in high seismicity areas. This could also reduce
the cost to repair non-structural damage, which is estimated to be approximately 70% of the
total repair cost for commercial buildings.
 Review processes around construction quality control and construction monitoring by the
designer and Territorial Authorities’ (TA’s) to ensure efficiency and confidence that the design
intent is achieved during construction.
 Consider setting up a review panel, perhaps a continuation of the Engineering Strategy Group
(ESG) or similar to USA practice where an independent consultant from an approved panel
reviews design and or construction.
Learnings from other commercial and Ministry of Education buildings should be applied to the
portfolio, for example:
 Stairs; review in accordance with Ministry of Business, Innovation and Employment (MBIE)
guidelines.
 Precast panels; especially connections and requirements for ductility.
 Shear walls; in line with interim design guidelines by Structural Engineering Society New
Zealand (SESOC).
 Cross bracing; particularly Reid Brace especially connections and requirements for ductility.
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Contents
Executive Summary .................................................................................................... i
1
Introduction ....................................................................................................... 1
2
Assessment Scope .............................................................................................. 1
2.1 Limitations ........................................................................................................................ 1
2.2 Infrastructure .................................................................................................................... 2
2.3 Peak Ground Acceleration ................................................................................................ 2
2.4 Geotechnical ...................................................................................................................... 7
2.5 Potential Structural Weaknesses .................................................................................... 12
3
Selection of Buildings ........................................................................................12
3.1 Considerations for Selection ........................................................................................... 12
3.2 Selection Criteria ............................................................................................................. 12
3.3 Buildings Selected ........................................................................................................... 12
4
Building Type Structural Review .......................................................................16
4.1 Rating System ................................................................................................................. 16
4.2 Flowcharts and Reference Material ................................................................................ 16
5
Key Findings .................................................................................................... 20
5.1 Summary of Building Results .........................................................................................20
5.2 Discussion/Analysis of Results ....................................................................................... 25
6
Conclusions ...................................................................................................... 30
6.1 General Conclusions .......................................................................................................30
6.2 Infrastructure Performance/Damage ............................................................................. 31
6.3 Block Specific Conclusions .............................................................................................. 32
7
Recommendations ........................................................................................... 32
7.1 Site Considerations – Buildings and Infrastructure ....................................................... 32
7.2 Process ............................................................................................................................ 33
7.3 Further Review ................................................................................................................ 33
8
Limitations....................................................................................................... 34
8.1 Other Site Risks............................................................................................................... 34
Appendix A - School Building Types ......................................................................... A1
A1 Two Storey Classroom Block .......................................................................................... A2
A2 Subfloor Framing ........................................................................................................... A3
A3 Pre 1930s Two Storey Block ........................................................................................... A4
Appendix B – Block Types by School ........................................................................ B1
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Appendix C – Building Type Performance Summary ................................................ C1
C1
Open Air Veranda block ................................................................................... C2
C1.1 Recommendations & Conclusions ................................................................................. C2
C2
Dominion block ................................................................................................ C3
C2.1 Recommendations & Conclusions ..................................................................................C3
C3
Canterbury block.............................................................................................. C4
C3.1 Recommendations & Conclusions ..................................................................................C5
C4
12 Classrooms double storey Block ................................................................... C6
C4.1 Recommendations & Conclusions ................................................................................. C6
C5
Open Plan Block ............................................................................................... C7
C5.1 Recommendations & Conclusions .................................................................................. C7
C6
CEBUS MK 1 & 2 ............................................................................................... C8
C6.1 Recommendations & Conclusions ................................................................................. C8
C7
CEBUS Modified (1990).................................................................................... C9
C7.1 Recommendations & Conclusions ................................................................................. C9
C8
Prefabs - Paul Wilkin Design .......................................................................... C10
C8.1 Recommendations & Conclusions ................................................................................ C10
C9
Nayland Block ................................................................................................. C11
C9.1 Recommendations & Conclusions ................................................................................ C11
C10 Hall with Sub-basement ................................................................................. C12
C10.1 Recommendations & Conclusions ................................................................................ C12
C11 Hall without Sub-basement ............................................................................ C13
C11.1 Recommendations & Conclusions ................................................................................ C13
C12 Portacom........................................................................................................ C14
C12.1 Recommendations & Conclusions ................................................................................ C14
C13 Subfloor Framing ........................................................................................... C15
C13.1 Recommendations & Conclusions ................................................................................ C15
C14 Pre 1930s 2 Storey Block ................................................................................ C16
C14.1 Recommendations & Conclusions ................................................................................ C17
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C15 1940s Single Storey Weatherboard Block ....................................................... C18
C15.1 Recommendations & Conclusions ................................................................................ C18
C16 1950s Double Storey ....................................................................................... C19
C16.1 Recommendations & Conclusions ................................................................................ C19
C17 1960s Nelson Block "Straight" ........................................................................ C20
C17.1 Recommendations & Conclusions ............................................................................... C20
C18 1960s Nelson Block "H Plan" .......................................................................... C21
C18.1 Recommendations & Conclusions ................................................................................ C21
C19 Nelson Single Storey ...................................................................................... C22
C19.1 Recommendations & Conclusions ............................................................................... C22
C20 S68 (school 68-72).......................................................................................... C23
C20.1 Recommendations & Conclusions ............................................................................... C23
C21 Secondary School Hall ................................................................................... C24
C21.1 Recommendations & Conclusions ............................................................................... C24
Appendix D – Geotechnical Description of School Standard Blocks ......................... D1
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1
Introduction
Opus International Consultants (Opus) has been commissioned by the Ministry of Education (“the
Ministry”) to review damage to school buildings caused by the recent Canterbury earthquakes.
This report was first issued on 10 February 2012 and has been updated to include:







Refinement to the intensity of shaking zonation to reflect the PGA contours, provided by GNS,
now available on the Canterbury Geotechnical Database1.
Review the Critical Structural Weaknesses (CSWs) in context of the current classification of
structural weaknesses for light-weight timber buildings.
Improve the data on damage for the various blocks based on information available to the
Ministry.
Improve the ground damage classification/zonation to identify the influence that ground
movement had on building damage.
Clarify the standard block types using the Catalogue of Standard Buildings produced by the
Ministry.
Include data from the standard block assessments.
Update the conclusions and recommendations to reflect the amendments to the report.
2 Assessment Scope
This report assesses the structural performance of a series of school building types located at over
40 school sites in Canterbury. The scope of work is to:


Provide a detailed and concise report for use by the Ministry on the impact of the recent
Christchurch earthquakes (September 2010, February 2011 and June 2011) on the Ministry’s
school buildings and infrastructure.
The purpose of this report is to highlight aspects of the buildings and infrastructure that
performed well / poorly to allow the Ministry to improve the resilience of their current and
future school buildings in Christchurch and throughout New Zealand.
2.1 Limitations
The structural assessments conducted by various structural consulting firms were reviewed along
with any information provided by the Ministry and the schools themselves. No additional
structural assessments were performed as per the scope of this project.
The reports reviewed consist of Rapid Assessment forms, which involves a walk around and
through the building (if safe to do so) looking for visible signs of significant structural damage.
This is specified as post-disaster Building Safety Evaluation endorsed by the MBIE (formerly
Department of Building and Housing). Following this, Detailed Engineering Evaluation (DEE)
reports have also been prepared for the Ministry, these generally involve a detailed visual
inspection and calculation of the existing structural capacity of the buildings compared against the
current building code. Where available these have been reviewed to verify the findings discussed in
this report.
1
canterburygeotechnicaldatabase.projectorbit.com
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The reports used for this review were completed by a range of consulting firms over an extended
period of time, and this information has been used without review. Opus takes no responsibility
for the reliability of these structural reports, nor the information from these reports that has been
used herein.
The standard building types considered for this study are not exhaustive. If none of the standard
building types match the school of interest, no conclusions should be taken from any similar
building types. The standard building types found in the Canterbury region differ from those found
in other regions. Therefore it is important to use the building type description to get an exact
match. The standard building type names are indicative only, as the same type of buildings may
have different names across the country.
2.2 Infrastructure
This report is focussed on the performance and damage of school buildings, a review of other
Ministry infrastructure is outside the scope of this report. From our involvement in infrastructure
repairs at a number of school sites Opus have formed and provided some conclusions on the
general performance of infrastructure.
2.3 Peak Ground Acceleration
The school buildings have sustained damage in both the 2010 Darfield and 2011 Christchurch
earthquakes. The overall damage resulting from the series of earthquakes is considered in this
report. No distinction is explicitly made between the different events, which may have resulted in
different types of damage. It is not possible to clearly state which events caused specific observed
damage. As an example, the 4 September earthquakes might have caused unobserved damage to
structural elements which failed during the 22 February earthquake.
The ground accelerations were recorded and are shown on Figure 1 and Figure 2, extracted from
the GNS report2. The peak ground acceleration (PGA) in the horizontal direction closely correlates
to the extent of damage caused by the earthquakes.
Webb T. H., Beaven J., Brackley H., Gerstenberger M., Kaiser A., McSaveney E., Reyners M., Somer-ville P., Van Dissen R., Wallace L.,
Bannister S., Berryman K., Fry B., Holden C., McVerry G., Pettinga J., Rhoades D., Stirling M., Villamor P., and Zhao J., ‘The Canterbury
Earthquake Sequence and Implications for Seismic Design Levels’, GNS Science Report 2011/128, July 2011.
2
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Figure 1 : Maximum horizontal and vertical PGA’s recorded during the 4 September 2010 earthquake at
GeoNet stations
Figure 2 : Maximum horizontal and vertical PGA’s recorded during the 22 February 2011 earthquake at
GeoNet stations
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Figure 3 and Figure 4 show banded summary contour maps of the ground shaking experienced in
Canterbury as a result of the September 2010 and February 2011 earthquakes overlaid with the
school locations, refer to Figure 7 for a full list of Ministry schools. The PGA contours have been
obtained from the Canterbury Geotechnical Database.
The four different bands are representative of the design level earthquakes where the ‘Return
period’ (R) factor relates to the various expected earthquake intensities for a building with a 50
year design life. The severity rating of each band relates to the annual probability of an earthquake
event, as shown in Table 2-1.
Table 2-1: Return Period Factor Range*
Description
Ru or Rs Return Period
Factor Range
Return Period Range
Severe
R ≥ 1.8
>1/2500
High
R = 1.0 to 1.8
1/500 to 1/2500
Moderate
R = 0.75 to 1.0
1/250 to 1/500
Low
R = 0.35 to 0.75
*based on new seismicity (Z=0.3)
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Z=0.3
Figure 3: Combined Peak Ground Acceleration - Christchurch
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Z=0.3
Figure 4: Combined Peak Ground Acceleration - Canterbury
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2.4 Geotechnical
Widespread liquefaction occurred during the 22 February event. Figure 5 and Figure 6 show the
foundation technical categories from the MBIE, overlaid with the school locations, refer to Figure 7
for a full list of Ministry schools. These maps provide an indication of the susceptibility to
liquefaction in the city and wider Canterbury.
Comments have been included in Table 5-1 to provide an indication of the extent of damage which
can be attributed to ground movement, and that which has resulted from ground shaking.
Reference can also be made to the maps in Figure 5 and Figure 6 which show the school locations
in relation to the extent of shaking and liquefaction.
2.4.1 Category
The geotechnical classification has been developed by the Ministry and will be available for
Canterbury schools to differentiate the classification from the MBIE Technical Categories for
residential properties (e.g. TC1 – TC3). The report incorporates these classifications where
available, alternatively where these are not available, the MBIE technical categories for the
neighbouring residential properties have been used.
GH1 Geotech Hill Category 1
Future land damage from subsidence or land slip is unlikely and there is no rock fall hazard. Likely
to be able to use standard foundations for buildings of a similar structure and size to those already
present on site.
GH2 Geotechnical Hill Category 2
There is risk from land slips, subsidence and / or a rock fall hazard. Specific engineered foundation
and rockfall mitigation design will be required.
GC1 Geotechnical Category 1
Future land damage from liquefaction or lateral spreading is unlikely. Likely to be able to use
standard foundations for buildings of a similar structure and size to those already present on site.
GC2 Geotechnical Category 2
Minor to moderate land damage from liquefaction or lateral spreading is possible in future
significant earthquakes. The use of standard timber piled foundations for simple single storey
buildings (up to average house size) with lightweight cladding and roofing and suspended timber
floors is likely to be acceptable. The use of enhanced concrete foundations that tie the structure
together for single storey buildings (up to average house size) with concrete slab floors is likely to
be required. Multi-storey and larger buildings may require a site-specific geotechnical
investigation and specific engineered foundation design.
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GC3 Geotechnical Category 3
Moderate to significant land damage from liquefaction or lateral spreading (< 500mm) is possible
in future significant earthquakes. Site-specific geotechnical investigation and specific engineered
foundation design is likely to be required.
GC4 Geotechnical Category 4
Significant land damage from lateral spreading (>500mm) is possible in future significant
earthquakes. Site-specific geotechnical investigation and specific engineered foundation design
will be required.
2.4.2 Data Reliability and Confidence
The reliability and confidence of geotechnical information varies depending on the level of
information available at the time of writing the respective school reports. This has been assessed
and commented on in the geotechnical reports when they have been completed by the respective
consultants however it has not been replicated or explicitly stated in this report. Readers are
directed to the source reports for further information of data reliability and confidence.
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Figure 5: Technical Categories - Christchurch
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Figure 6: Technical Categories - Canterbury
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Figure 7: Full List of Ministry Schools
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2.5 Potential Structural Weaknesses
A “Critical Structural Weakness” (CSW) refers to a component of a building that could contribute
to increased levels of damage or cause premature collapse of a building.
Apart from one pre 1930s 2 storey block, no blocks were found to have CSWs. Some school
buildings however, do have structural deficiencies or weaknesses that adversely affect the
building’s seismic performance. These weaknesses are not considered to be critical to life safety or
collapse. In these cases the term ‘structural weakness’ has been used.
3 Selection of Buildings
3.1 Considerations for Selection
The aim of the block selection process was to provide a representative of the range of school
buildings typically found throughout New Zealand. Primary, intermediate, and secondary school
building types were considered to account for the differences in building form and scale between
school sectors. Although some of the buildings are suitable for more than one school sector, the
difference in the building footprint between sectors is significant.
Given the relative size of the greater Wellington region and its location in a high seismicity area,
additional effort was made to find block types common in the Wellington region. Notable block
types in Wellington include:
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
1950s Henderson Blocks: Heretaunga College (none of these have been located for this report).
S68 Blocks (late 60s early 70s): Porirua College, Wainuiomata High.
Nelson Library Blocks: Heretaunga College, Porirua College, Wainuiomata High.
3.2 Selection Criteria
The selection of the school buildings was made based on the following criteria:




Location in the Christchurch area.
Representative of New Zealand school building types.
Range of earthquake damage from minor to significant. and,
Access to existing structural reports and in some cases, structural drawings.
3.3 Buildings Selected
The following buildings have been selected to represent standard types of buildings. The full
description of each building type is presented in Appendix C.
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Table 3.1: Standard Block Locations
Standard Type of Building
Location
Primary and Intermediate Schools
Shirley Intermediate – 60 Shirley Road, Shirley, Chch
Wharenui Primary – 32 Matipo Street, Riccarton, Chch
Open Air Veranda Block
Wairakei Primary – 250 Wairakei Road, Bryndwr, Chch
Bamford Primary – 6 Gould Crescent, Woolston, Chch
Hammersley Park Primary – 90 Quinns Road, Shirley, Chch
Dominion Block
Banks Avenue Primary – 91 Banks Avenue, Dallington, Chch
Addington Primary – 22 Brougham Street, Addington, Chch
Thorrington Primary – 22A Colombo Street, Lower Cashmere,
Chch
Heathcote Valley Primary – 61 Bridle Path Road, Heathcote
Valley, Chch
Hoon Hay Primary – 91 Sparks Road, Hoon Hay, Chch
Freeville Primary – 1 Sandy Avenue, North New Brighton,
Chch
Canterbury Block
Banks Avenue Primary – 91 Banks Avenue, Dallington, Chch
Russley Primary – 75 Cutts Road, Avonhead, Chch
Sumner Primary – 15 Colenso Street, Sumner, Chch
Darfield High – 16 Ross Street, Darfield, Canterbury
Central New Brighton Primary – 140 Seaview Road, New
Brighton, Chch
Twelve Classroom Double
Storey Block
Manning Intermediate – 50 Hoon Hay Road, Hoon Hay, Chch
Branston Intermediate – 35 Amyes Road, Hornby, Chch
Shirley Primary – 11 Shirley Road, Shirley, Chch
Open Plan Blocks
Fendalton Open Air School – 168 Clyde Road, Fendalton,
Chch
Central New Brighton Primary – 140 Seaview Road, New
Brighton, Chch
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Standard Type of Building
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Location
Heathcote Valley Primary – 61 Bridle Path Road. Heathcote
Valley, Chch
Queenspark Primary – 222 Queenspark Drive, Parklands,
Chch
Bromley Primary – 33 Keighleys Road, Bromley Chch
Banks Avenue Primary – 91 Banks Avenue, Dallington, Chch
Hoon Hay Primary – 91 Sparks Road, Hoon Hay, Chch
Shirley Primary – 11 Shirley Road, Shirley, Chch
CEBUS MK I & II
Van Asch Deaf Education Centre (Block K) – 38 Truro Street,
Sumner, Chch
Heathcote Valley Primary – 61 Bridle Path Road, Heathcote
Valley, Chch
St Martins Primary – 24 Albert Terrace, St Martins, Chch
CEBUS 4
Bamford Primary – 6 Gould Crescent, Woolston, Chch
Bromley Primary – 33 Keighleys Road, Bromley Chch
CEBUS Modified (1990)
Fendalton Open Air Primary – 168 Clyde Road, Fendalton,
Chch
Russley Primary – 75 Cutts Road, Avonhead, Chch
Sumner Primary – Colenso Street, Sumner, Chch
Paul Wilkin Design
Banks Avenue Primary – 91 Banks Avenue, Dallington, Chch
Middleton Grange – 50 Acacia Avenue, Riccarton, Chch
Nayland
Burnside High – 151 Greers Road, Burnside, Chch
Kaiapoi Borough Primary – 20 Hilton Street, Kaiapoi
Halls with Sub-basement
under stage
Russley Primary – 75 Cutts Road, Avonhead, Chch
Hammersley Park Primary – 90 Quinns Road, Shirley, Chch
Avonhead Primary – 55 Avonhead Road, Avonhead, Chch
Hall without Sub-basement
under stage
Portacom
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Linwood North Primary – 221 Woodham Road, Linwood,
Chch
Burnside High – 151 Greers Road, Burnside, Chch
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Standard Type of Building
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Location
Hoon Hay Primary – 91 Sparks Road, Hoon Hay, Chch
St Martins’ Primary – 24 Albert Terrace, St Martins, Chch
Subfloor Framing
Mt Pleasant Primary – 82 Major Hornbrook Road, Chch
Secondary Schools
Hagley Community College – 510 Hagley Avenue, Addington,
Chch
Pre 1930s 2 Storey Block
Avonside Girls’ High – 180 Avonside Drive, Avonside, Chch
Christchurch Boys’ High – Straven Road, Riccarton, Chch
Papanui High – 30 Langdons Road, Papanui, Chch
1940’s Single Storey
Weatherboard
Heaton Intermediate – 125 Heaton Street, Merivale, Chch
Wairakei Primary – 250 Wairakei Street, Bryndwr, Chch
Linwood College – 85 Aldwins Road, Linwood, Chch
Cashmere High – 172 Rose Street, Somerfield, Chch
1950s Double Storey
Avonside Girls’ High – 180 Avonside Drive, Avonside, Chch
Rangiora High – 125 East Belt, Rangiora
Nelson Block "Straight
Block"
Avonside Girls’ High (Gresson Block) – 180 Avonside Drive,
Avonside, Chch
Papanui High (Plimsol Block) – 30 Langdons Road, Papanui,
Chch
Burnside High – 151 Greers Road, Burnside, Chch
Linwood College – 85 Aldwins Road, Linwood, Chch
Nelson Block "H Plan"
Mairehau High – 440 Hills Road, Mairehau, Chch
Cashmere High – 172 Rose Street, Somerfield, Chch
Lincoln High – 25 Boundary Road, Lincoln
Nelson Single Storey
Mairehau High – 440 Hills Road, Mairehau, Chch
Shirley Boys’ High – 59 North Parade, Shirley, Chch
Kaiapoi High – 101 Ohoka Road, Canterbury
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Standard Type of Building
Location
S68 (schools 1968) and MKII
in 1972
Hornby High – 180 Waterloo Road, Hornby, Chch
16
Lincoln High – 25 Boundary Road, Lincoln
Secondary school Hall
Papanui High – 30 Langdons Road, Papanui, Chch
Cashmere High – 172 Rose Street, Somerfield, Chch
4 Building Type Structural Review
For this review, school buildings have been identified by their standard type. A “Building
Performance Assessment” has been prepared and undertaken for each building by an Opus
Structural Engineer to assess the damage, consider the repair work undertaken and or required,
identify the structural weaknesses and rate the building.
4.1 Rating System
A rating system has been implemented to simplify the performance evaluation of the buildings and
provide comparison between the different types. The Table 4-1 shows the rating descriptions
which have been used by Opus to rate the performance of each building.
Table 4-1: Summary of Performance/Damage Rating System
Rating
Number
Rating
Title
Performance/Damage Description
1
Very Well
It withstood the earthquake without any significant damage.
2
Well
It withstood the earthquake with minor non-structural
damage which required minor repairs prior to occupancy.
3
Fair
It had extensive non-structural and/or minor structural
damage. It needed repairs prior to usage.
4
Poor
It had significant structural damage affecting overall
structural integrity.
5
Very Poor
The building suffered severe structural damage and required
urgent strengthening or demolition.
4.2 Flowcharts and Reference Material
All of the information used about the various school buildings and the conclusions drawn after
completion of the Building Performance Assessment forms, are contained in the Appendices A - C.
This material includes:


Flowchart of types: The flowchart is presented in Figures 8 - 11. These have been designed to
help identify the type of building.
School block ordered by type: All block types are listed along with their locations.
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

17
School blocks ordered by name: Schools are listed with the types of building that have been
reviewed as part of this work.
Each type of building reviewed has its datasheet containing general photos along with specific
earthquake damage photos. The summary of each building is listed in short form along with
the rating and the earthquake intensity zone.
Figure 8: Single storey relocatable classroom flowchart identification tool
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Figure 9: Single storey permanent classroom flowchart identification tool
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Figure 10: Double storey classroom flowchart identification tool
Figure 11: Non-classroom building flowchart identification tool
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5 Key Findings
5.1 Summary of Building Results
Table 5.1 shows the different building types with their overall rating and comments considering
ground shaking and geotechnical category (refer to Figure 3 to 5).
Table 5-1 - Standard block summary
Building Type
Open Air
Veranda Block
Dominion Block
School Name
Shaking
Intensity
Geotech
Category
Rating
Shirley
Intermediate
High
TC3
3
Wharenui Primary
High
TC2
2
Bamford Primary
Severe
GC2
2*
Wairakei Primary
Low
TC2
2
Banks Avenue
Primary
High
Blocks 1, 2
and 4- GC4
(>500mm of
lateral spread)
5
Hammersley Park
Primary
Moderate
TC3
3
Addington
Primary
High
GC2
2*
High
TC2
4
Severe
TC2
1
High
GC2
2
Low
GC3
2
Banks Avenue
Primary
High
Blocks 1, 2
and 4- GC4
(>500mm of
lateral spread)
2
Russley Primary
Low
TC1
2
Darfield Primary
High
N/A Rural and
Unmapped
3
Sumner Primary
Severe
TC2
1
Central New
Brighton Primary
Moderate
TC3
2
Thorrington
Primary
Heathcote Valley
Primary
Hoon Hay
Primary
Freeville Primary
Canterbury
Block
Comments 3,4
Shaking damage primarily due to
ground deformation.
Connection of sub-floor framing to
building assessed to be 11%NBS.
Once strengthened, building is
assessed to be greater than 34%NBS.
Banks Avenue Primary ground
deformation contributed to damage.
Plan irregularity (structural
weakness) due to full length windows
on one side of building; may cause
excessive deformation and potential
falling hazard from the brick veneer.
The assessed capacity is 70%NBS
(NZSEE, Sp = 0.5, Z = 0.3).
The damage to Thorrington Primary
and Banks Avenue Primary is mostly
due to ground deformation.
The assessed capacity is 41%NBS
(NZSEE, Sp = 0.5, Z = 0.3).
* These ratings are based on the DEE summary report as no primary source information about the damage is available.
3
4
Notes from standard reports and assessments by Opus and others.
Establishing the Resilience of Timber Framed School Buildings in New Zealand; 2014 NZSEE Conference
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Building Type
Twelve
Classrooms
Double Storey
Open Plan
Blocks
CEBUS 1
CEBUS 2 (MK I
& II)
21
School Name
Shaking
Intensity
Geotech
Category
Rating
Comments 3,4
Manning
Intermediate
Moderate
TC3
2
Branston
Intermediate
Moderate
GC1
3
Lower intensity zone samples.
Limited conclusion but wall
irregularity may be a structural
weakness.
No significant ground deformation.
Shirley Primary
High
TC3
2
Fendalton Open
Air Primary
Moderate
TC3
2
Central New
Brighton Primary
Moderate
TC3
1
Bromley Primary
Severe
GC2
1*
Heathcote Valley
Primary
Severe
GC1/GH1
3
Queenspark
Primary
Low
TC2
2
Heathcote Valley
Primary
Severe
GC1/GH1
1*
Banks Avenue
Primary
High
Blocks 1, 2
and 4- GC4
(>500mm of
lateral spread)
1
Hoon Hay
Primary
High
GC2
1*
Heathcote Valley
Primary
Severe
GC1/GH1
1*
Shirley Primary
High
TC3
1
Van Asch Deaf
Education Centre
Severe
GC1
2
Central timber framed shear walls
assessed to be 38%NBS.
No structural weaknesses for the
superstructure.
No significant ground deformation.
Resistant to damage due to ground
deformation.
No structural weaknesses for the
superstructure.
Superstructure assessed to be
49%NBS (NZSEE, Sp = 0.5,
Z = 0.3).
Foundations assessed to be
approximately 40%NBS.
No significant ground deformation.
Resistant to damage due to ground
deformation.
Simple design with a portal frame
bracing system. Monitor condition of
the gangnail plates which provide the
connection at the external frame
connections. These might start to
work loose.
No structural weaknesses for the
superstructure.
Superstructure assessed to be
49%NBS (NZSEE, Sp = 0.5,
Z = 0.3).
Foundations assessed to be
approximately 40%NBS.
* These ratings are based on the DEE summary report as no primary source information about the damage is available.
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Building Type
School Name
Shaking
Intensity
Geotech
Category
Rating
Fendalton Open
Air Primary
Moderate
TC3
1
Russley Primary
Low
TC1
1
Woolston Primary
Severe
GC2
1*
St Martin’s
Primary
High
GC2/GH1
2*
Bamford Primary
Severe
GC2
1*
Bromley Primary
Severe
GC2
2*
Banks Avenue
Primary
High
Blocks 1, 2
and 4- GC4
(>500mm of
lateral spread)
2
Sumner Primary
Severe
TC2
1
Middleton Grange
Moderate
TC1
1
Burnside High
Low
TC1
2
Kaiapoi Borough
Primary
Moderate
GC3
2
Russley Primary
Low
TC1
2
Hammersley Park
Primary
Moderate
TC3
2
Avonhead
Primary
Low
TC1
2
Linwood North
Primary
High
GC2
3
Burnside High
Low
TC1
1
Hoon Hay
Primary
High
GC2
2
CEBUS
Modified (1990)
CEBUS 3
CEBUS 4
Paul Wilkin
Design
Nayland
Hall with Subbasement
Hall without
Sub-basement
Portacom
22
Comments 3,4
Resistant to damage due to ground
deformation.
Similar structure to the CEBUS Mk
1&2. Lower intensity zone samples
with no damage.
No structural weaknesses for the
superstructure.
Superstructure assessed to be
49%NBS (NZSEE, Sp = 0.5,
Z = 0.3).
Foundations assessed to be
approximately 90%NBS.
No significant ground deformation.
Resistant to damage due to ground
deformation.
No significant ground deformation.
Resistant to damage due to ground
deformation.
No structural weaknesses for the
superstructure.
Superstructure assessed to be
49%NBS (NZSEE, Sp = 0.5,
Z = 0.3).
Foundations assessed to be
approximately 40%NBS.
No significant ground deformation.
Performed well subjected to ground
movement. Foundations are easily relevelled.
Lower intensity zone samples.
Limited conclusions can be drawn.
No significant ground deformation.
Plan and vertical irregularity. This
may be a structural weakness due to
the tendency of the two sections of
building to respond differently.
No significant ground deformation.
Roof diaphragm action and wall
bracing provide additional bracing.
Lightweight cladding materials
reduce the seismic demand on the
structure.
No significant ground deformation.
Performed well subjected to ground
movement.
* These ratings are based on the DEE summary report as no primary source information about the damage is available.
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Building Type
Subfloor
Framing
Pre 1930’s 2
Storey Block
1940’s Single
Storey
weatherboard
1950’s Double
Storey
23
School Name
Shaking
Intensity
Geotech
Category
Rating
Comments 3,4
St Martin’s
Primary
High
GH1
3
Mt Pleasant
Primary
Severe
N/A Port Hills
& Banks
Peninsula
3
The foundation/structure connection
details are critical as they could fail
during large ground deformation or
intense shaking
Hagley
Community
College
High
TC2
2
Avonside Girls’
High
High
GC2-3.
5
Christchurch
Boys’ High
High
TC3
2
Papanui High
Low
GC2
2
Heaton Normal
Intermediate
Moderate
TC3
3
Wairakei Primary
Low
TC2
1
Linwood College
High
GC3 (CPT
>100mm)
3
Rangiora High
Low
N/A Rural and
Unmapped
2
Cashmere High
High
TC3
3
Avonside Girls’
High School
High
GC2-3
4
Avonside Girls’
High
High
GC2-3. See
plot provided.
4
Papanui High
Low
GC2
1
1960’s Nelson
Block “Straight”
These buildings built in the 1930s are
likely to have CSW, such as
unreinforced brick walls that may
become a falling hazard.
Strengthening works in the 1990’s
carried out to address most
earthquake prone building issues
provides an explanation for their
relatively good performance.
These buildings are heavy and stiff.
Extensive damage at Avonside Girls’
High School due to ground
movement.
This lightweight and low building
performs well under seismic loads.
Ground deformation at Heaton
Normal Intermediate caused
significant damage to foundations
and superstructure cracking.
Heavy concrete structure susceptible
to ground deformation. This occurred
at Linwood College and Avonside
Girls’ High School.
Insufficient bracing (potential CSW)
in the longitudinal direction due to
the clerestory windows between the
concrete columns; may result in
significant damage to beams and
columns.
Extensive damage at Avonside Girls’
High School due to ground
deformation.
Two storeys of window openings
with masonry veneer beneath the
ground floor windows cause plan
irregularity (structural weaknesses).
Strengthening works in the 1990’s2000’s carried out to address most
earthquake prone building issues
which explains their relatively good
performance.
* These ratings are based on the DEE summary report as no primary source information about the damage is available.
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Building Type
School Name
Shaking
Intensity
Geotech
Category
Rating
Burnside High
Low
TC1
2
Linwood College
High
GC3
1
Mairehau High
Moderate
TC2
1
Cashmere High
High
TC3
3
Lincoln High
High
TC1
1
1960’s Nelson
Block “H Plan”
1960-70’s Single
Storey
Weatherboard
Mairehau High
Moderate
TC2
1
Shirley Boys’
High
High
TC3
3
Kaiapoi High
Moderate
GC2
2*
Hornby High
Low
TC1
1
S68 (School 6872)
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24
Comments 3,4
Two storey timber framed building in
general “H” formation. Lacks lateral
load resisting elements on the end
walls. Lateral load resisting system
in both directions relies in part on
timber columns cantilevering above
braced walls. These can be
considered as structural weaknesses.
Building assessed to be 36%NBS
with concrete stairs or 38%NBS with
timber stairs (NZSEE, Sp = 0.5,
Z = 0.3). General performance of the
building is likely to be better than the
figures shown above. Higher
capacities may be gained by
estimating the impact of factors such
as load redistribution, secondary
structural elements, energy
dissipation and conservatism in
estimated strength capacities of the
structural elements.
These buildings generally performed
adequately in Christchurch and are
unlikely to collapse during a
moderate earthquake.
Strengthening works in the 1990’s2000’s carried out to address most
earthquake prone building issues
which explains their relatively good
performance.
The majority of damage at Cashmere
High School is due to ground
deformation.
At Shirley Boys’ High School, most
of the damage recorded was due to
ground deformation. The lack of
bracing between the windows is a
structural weaknesses.
Lateral load resistance in both
directions provided by reinforced
block walls and built in reinforced
block piers.
Some loads at roof level transferred
to block walls through light,
primarily gravity, steel frames. This
may be considered a structural
weakness, but is unlikely to lead to
collapse during a moderate
earthquake.
The damage at Kaiapoi High School
is mostly due to ground deformation.
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Building Type
School Name
Shaking
Intensity
Geotech
Category
Rating
25
Comments 3,4
* These ratings are based on the DEE summary report as no primary source information about the damage is available.
Secondary
School Hall
Aranui Block
Lincoln High
High
TC1
1
Papanui High
Low
GC2
1
Cashmere High
High
TC3
1
Woolston Primary
Severe
GC2
1*S
Low and moderate intensity zone
samples and no damage.
No significant ground deformation.
* These ratings are based on the DEE summary report as no primary source information about the damage is available.
5.2 Discussion/Analysis of Results
Table 5-2 provides a brief overview of building performance by type, relating the level of shaking
with the level of performance in broad qualitative terms.
Buildings that have experienced high or severe shaking but have low damage are identified as high
performers in the upper left (green shaded) cells. In contrast, those buildings that have significant
damage whilst only experiencing low or moderate shaking are identified as poor performers and
are shown in the lower right (red shaded) cells.
These results should be read with due consideration for the many factors that affect the behaviour
of a structure, including:



The intensity zone in which the building was located. The “Low” zone buildings should be
considered as not seismically tested. When looking at results for the “Moderate” and “Severe”
zones, the buildings have been considered to have been tested by seismic activity.
The type of shaking or the ground deformation effect differs from site to site.
Blocks which have been identified as a certain building type and built in a specific era may have
been modified more recently. This has generally not been taken into account for this review.
Note that the red text in italics indicates that this block has a geotechnical category of 3-5 (1 being
“good” ground, 5 being red zone).
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Table 5-2: Performance Summary
Performance/Damage Rating
Severe
1
2
3
4
5
Very Well
Well
Fair
Poor
Very Poor
Canterbury (2)
Open Plan
CEBUS 1
Open Air Veranda
CEBUS 2
CEBUS 2
CEBUS 3
CEBUS 4
Subfloor Framing (unmapped)
Open Plan
Paul Wilkin
Aranui
Open Air Veranda
Open Air Veranda
CEBUS 2
Canterbury & Canterbury
Canterbury (unmapped)
CEBUS 2
Paul Wilkin
Dominion
Single Storey WB
Open Plan
Single Storey WB
Secondary Hall
CEBUS 4
1950s 2 storey (2)
Secondary Hall
Portacom
Nelson H
Nelson H
Pre-1930 2 Storey
Subfloor Framing
Pre-1930 2 Storey
Hall without SB
High
Shaking
Intensity
Moderate
Open Plan
Canterbury
CEBUS M
Open Plan
Nelson H
12 Classrooms 2 storey
Dominion
Nayland
Hall SB (2)
12 Classrooms 2 storey
Single Storey WB
S68
Canterbury
1950s 2 storey
Nelson Straight
Dominion
Pre-1930 2 storey
Single storey WB
Open Air Veranda
Low
CEBUS M
Nayland
Single Storey WB
Canterbury
Secondary Hall
Hall SB & Hall without SB
Portacom
1950s 2 storey (unmapped)
Nelson Straight
Nelson H
S68
Open Plan
Single Storey WB
Note that the Italics and red text indicate this block has a geotechnical category of 3-5 (1 being “good” ground, 5 being red zone)
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5.2.1 Earthquake Damage
When liquefaction and ground deformation have been observed, a large proportion of the building
damage is likely to be attributable to ground deformation. Consequently, a site geotechnical
assessment should be performed in addition to building type assessment to show which blocks are
more vulnerable to shaking and ground deformation.
5.2.2 Building Type Modifications
Different types of modifications such as retrofitting and strengthening of buildings may have been
undertaken. For example, the MoE directed that heavy roof tiles be removed following a report
completed by Connell Wagner Limited5; a lightweight roof improves seismic performance.
5.2.3 Construction Issues
Some construction problems were noted during the overall assessment process. For example, the
lack of sufficient connections from the brick veneer to the timber walls which can be a hidden
structural weakness. Variable mortar quality also affects the performance of brick veneer.
Investigation findings into the performance of veneer ties has been undertaken by Opus (refer to
Opus methodology report for MoE). Investigation into non-structural veneers in Canterbury and
around New Zealand continues and information currently available has found that the effectiveness
of installed ties is highly variable. An early recommendation from this work is to carry out a veneer
tie investigation in areas of high seismicity, where veneer could be a potential fall hazard. If ties
are adequate, the veneer performance is likely to be good.
5.2.4 Analysis of Results
Table 5-2 illustrates how the different block types have performed under varying shaking
intensities and geotechnical conditions. The following describes performance trends observed.
5.2.4.1 Data Scatter
There are a number of blocks of the same type which have a different rating, for example the
Canterbury block for high shaking intensity is rated 2, 3, and 4 (well, fair and poor) at different
sites. This sort of scatter is normal in earthquake damage data, and is due to a number of factors
including:




Variation in shaking due to local soil effects;
Different block orientation;
Different block construction details, due to age and architectural finishes; and,
The limitations and simplifications made in the assessment.
Connell Wagner Limited, ‘Technical Guidelines for Structural Mitigation Work’, www.minedu.govt.nz, July
2003 – revision 7
5
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5.2.4.2 Best Performing Blocks
All of the timber framed standard school block designs performed well. The most common blocks
in the review; Canterbury, Open Plan, and CEBUS all performed “very well” or “well”, even in high
or severe shaking intensity areas.
Generally, the high performers were blocks which had tolerated ground deformation with minimal
damage. The reasons for the lightweight and ‘prefab’ type blocks performing well are:



The re-locatable classrooms are designed to be lightweight so they can be easily lifted;
Lightweight cladding means less seismic mass and therefore lower demand on the structure;
and,
The foundations are typically timber piles with timber subfloor frames which can accommodate
differential movement without significant structural damage, although linings may be affected.
The high performing blocks with low damage (rating 1 and 2) with high or severe shaking and high
geotechnical category were:






CEBUS 2;
Hall;
Paul Wilkin;
Canterbury Block;
Pre 1930s 2 storey; and,
Nelson H.
With the exception of the pre 1930s 2 storey block and Nelson H block, all of these buildings are
single storey comprising a lightweight timber frame. The pre 1930’s 2 storey blocks are essentially
unreinforced masonry (URM) structures and would typically be expected to have a poor
earthquake response. However, at Christchurch Boys High School, extensive structural
strengthening works were completed in the 1990s which significantly reduced damage.
Blocks with low damage (rating 1 and 2) with high or severe shaking intensity and a low
geotechnical category (GC1-2 “good” ground) were:








Canterbury Block;
Paul Wilkin;
Single Storey Weatherboard;
Hall;
CEBUS 2;
Open Air Veranda;
Open Plan; and,
Portacom.
All of these buildings are lightweight timber framed structures, generally having lightweight roof
cladding. These buildings have been shown to perform very well in earthquakes due to the high
ductility, flexibility and strength of light timber frame construction.
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5.2.4.3 Blocks with Significant Damage
Blocks with significant damage (rating 3 and 4) with high shaking and high geotechnical category
(GC3-5) were:






Open Air Veranda;
Dominion;
Single Storey WB;
1950s 2 storey;
Nelson Straight; and,
Nelson H.
With the exception of the 1950s 2 storey blocks, the high damage rating is due to substantial land
deformation rather than structural damage due to shaking. These structures are of lightweight
timber framed construction and although the Nelson blocks can have structural weaknesses, these
were remediated with structural strengthening in the 1990s.
The 1950s 2 storey blocks are heavy reinforced concrete structures, potentially having insufficient
longitudinal bracing due to clerestory windows. Two of these blocks were also subjected to land
deformation, further increasing the observed damage.
Blocks with severe damage (rating 5) with high shaking, coupled with both differential settlement
and ground deformation were:


Dominion Block; and,
Pre-1930s 2 storey;
The Dominion Block was located at Banks Avenue Primary. This site has a geotechnical category of
GC4, with significant lateral spread expected. Although the building comprises a relatively
lightweight timber frame with brick veneer, more damage was observed compared with other
blocks of this type due to significant land deformation.
The Pre-1930s 2 storey block which performed poorly was located at Avonside Girls High. This site
suffered extensive land deformation. Despite the strengthening in the 1990s, the ground
deformation caused significant damage to this heavy brittle building.
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6 Conclusions
Due to the qualitative nature of this review, the conclusions have been separated into three
categories;
6.1 General Conclusions
6.1.1 Building Types


70 school buildings classified into 25 types have been reviewed.
The majority of school buildings reviewed are single storey. The remainder are a maximum of
2 storeys.
6.1.2 Safety/Occupancy





There were no fatalities on school sites during the Canterbury earthquake sequence.
Some injuries occurred, mostly resulting during egress.
Potential / critical structural weaknesses did not result in collapse of any school buildings but
did result in additional damage.
The Ministry’s earthquake strengthening programme has been effective, as it prevented
building collapse, provided a safe environment for teachers and students, and limited damage
to buildings that would otherwise have been more severely affected.
We understand that prior to the earthquakes, a programme of replacing glass with safety glass
in windows and doors along exit routes had been implemented. This appears to have been
effective as there has been very few reported instances of broken glass.
6.1.3 Building Performance/Damage









Lightweight timber framed buildings have performed very well and generally in excess of their
calculated capacity.
Seismic retrofit work undertaken has been effective.
A large proportion of building damage was due to ground deformation.
Lightweight buildings with suspended timber floors on shallow footings generally
accommodate ground deformation well and can often be quickly and cost effectively re-levelled.
Overhead heavy building services or items unsecured on shelves can be a falling hazard.
Most heavy roofs have been removed and replaced with lightweight material, this has reduced
the seismic load and subsequent observed damage.
Where blocks have been joined together and the alignment of the principle axes are no longer
maintained such that the footprint is not symmetrical, i.e. joined together to form a T shaped
footprint, increased damage was observed.
Heavy veneer cladding increases damage to internal linings.
Overhead heavy veneer can be a falling hazard if not well tied to timber framing, particularly
above doors and windows.
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6.1.4 Process




There is inconsistency around the naming of school buildings.
There is no reliable database of drawing information for the building portfolio.
The post-earthquake inspection regime adopted by MoE has been effective.
Retrofit and assessment of buildings in some cases has not adequately addressed global site
issues, such as liquefaction related lateral spread at Jobberns/Gresson Blocks at Avonside Girls
High.
6.2 Infrastructure Performance/Damage
6.2.1 Water



School water supply systems generally performed well, particularly flexible pipework
(polyethylene). Older galvanised pipe was more susceptible to damage, mostly in the areas
where significant ground movement occurred, mainly due to its inherent rigidity and
deterioration over time.
For most urban school sites the critical factor was the non-availability of water from the Council
supply.
In the immediate term this was managed by installing large plastic water tanks which were
filled by potable water. Ministry of Health guidelines required that these tanks be sterilised,
and filled with potable water. Water stored this way needed to be chlorine-dosed regularly to
maintain potability. In many sites once water supply from the Council system was restored,
tanks were drained and left onsite. This was a contingency measure to manage ongoing risk,
requiring only 24 hours stand-down time for sterilisation during the aftershock sequence. The
majority have now been removed.
6.2.2 Sewer


Older pipework systems, particularly earthenware and reinforced concrete were least able to
withstand ground movement. This was often compounded by pre-existing deterioration due to
age. These systems tended to pull apart easily, allowing groundwater and silt from liquefaction
to enter pipelines and clog them. Newer systems constructed with PVC have more material and
connective flexibility and were able to withstand a greater amount of ground movement while
remaining intact. At some sites with PVC pipework, even when pipe grades have flattened as a
result of pipe movement, sewer systems at the school have remained operational, providing a
reasonable level of service to the school.
For most urban schools, the critical factor was the damage to the Council sewer systems in the
street. This meant that even if pipework within the site had sustained little damage, schools
still needed emergency measures. This was managed by portaloos at some sites, while others
installed large sewage holding tanks (similar to the ones for water supply), which the school’s
wastewater was pumped into. These tanks were emptied frequently. Once Council sewer
service was restored to sites, some schools have retained the emptied tanks onsite as a
contingency measure to manage future risk.
6.2.3 Stormwater

The issues with stormwater are similar to those for sewerage, with the exception that temporary
measures for stormwater service were not implemented. Instead, schools with damaged
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
32
stormwater systems are experiencing more frequent ponding on site as water is less able to
drain away. This presents nuisance (puddles and mud) and slip hazards in winter (freezing).
Repairs to stormwater systems are potentially costly due to a combination of very old systems
still in existence, and the need to comply with current building code requirements. In the sites
with the most severe damage, replacement of the entire stormwater system is the only
compliant option, which can be expensive.
6.2.4 Hardstand
Options for hardstand repairs range from the ‘do minimum’ to ‘full design life’ approach, with the
former aimed at repairing superficial defects and restoring immediate levels of service but
accompanied by the risk of ongoing repairs. The ‘full design life’ approach involves full
remediation of the hardstand surface, specifically designed to mitigate against known risks (such as
liquefaction or lateral spread) by inclusion of engineering measures such as geotextiles and
geogrids, with the aim of lessening the cost of repair in a future earthquake event.
6.3 Block Specific Conclusions
6.3.1 Block Performance/Damage



7
The open plan blocks have minimal bracing which increases frame distortion and damage.
Some CEBUS type buildings have external nail plates that have failed during shaking without
resulting in collapse. These can be simply retrofitted.
One of the Pre-1930’s Two Storey Block’s has Potential Critical Structural Weaknesses while up
to 11 others have structural weaknesses.
Recommendations
Following this structural review, our recommendations for the Ministry have been separated into
three categories.
7.1 Site Considerations – Buildings and Infrastructure
The following items can be implemented immediately by the Ministry to reduce the risk during a
future emergency:




An egress and evacuation plan should be put in place for each school site. The main issues are
concerning stuck doors due to differential settlement and potential fall hazards. The assembly
point should also be considered.
Overhead falling hazards relating to poorly tied brick veneer, heavy building services or items
on shelving should be assessed, and if required secured or removed to a lower height.
Consideration should be given to assessing and, if required, strengthening, or removing the
veneer at height to mitigate this risk in a future significant earthquake event. Lowering the
veneer will have the added benefit of reducing the seismic load on the buildings’ structure and
improving its overall performance.
Consideration should be given to upgrading site infrastructure during significant
developments. This would reduce the extent of aged, frequently extended, brittle pipe networks
present on many school sites.
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


33
Consideration should be given to the assessment of schools’ existing infrastructure networks,
for their condition and capacity i.e. compliance and vulnerability. This would indicate a need
for the upgrade of any existing infrastructure with newer, more robust systems. This also
reduces the risk of major costs associated with repairing older systems, when repairs carried
out in the future might trigger the requirement for a Building Consent. Discussion with
Councils should also be considered to seek clarity on compliance requirements.
Consideration should be given to contingency measures for lifeline services (water supply &
sewer).
Consider options for hardstands that include ‘full design life’ to mitigate known geotechnical
risks.
7.2 Process
In addition to the items in section 7.1, the following items should be implemented by the Ministry
to improve the quality and consistency of additional design and remediation works throughout the
portfolio.




Issue minimum standard brief and guidelines for engineering assessment and design which
embodies current ‘best practice’. (We note that the Ministry have subsequently issued
guidelines on importance level for retrofit and new design).
Consider adopting damage resistant designs in high seismicity areas. This could also reduce
the cost to repair non-structural damage, which is estimated to be approximately 70% of the
total repair cost for commercial buildings.
Review processes around construction quality control and construction monitoring by the
designer and Territorial Authorities’ (TA’s) to ensure efficiency and confidence that the design
intent is achieved during construction.
Consider setting up a review panel, perhaps a continuation of the Engineering Strategy Group
(ESG) or similar to USA practice where an independent consultant from an approved panel
reviews design and or construction.
7.3 Further Review
This report has involved a review of existing Ministry documentation on a selection of typical
blocks. However other learnings from commercial and Ministry buildings should also be applied to
the portfolio, for example:




Stairs; review in accordance with Ministry of Business, Innovation and Employment (MBIE)
guidelines.
Precast panels; especially connections and requirements for ductility.
Shear walls; in line with interim design guidelines by Structural Engineering Society New
Zealand (SESOC).
Cross bracing; particularly Reid Brace especially connections and requirements for ductility.
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34
8 Limitations
8.1 Other Site Risks
This assessment has only considered the hazards relating to earthquakes, and damage due to the
Canterbury earthquakes. There are other risks which should be considered by the MoE on a site
wide basis, including flooding, tsunami etc.
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A1
Appendix A - School Building Types
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A2
Appendix A describes the typical school building types used in New Zealand which are not included
in the Catalogue of Standard School Building Types August 2013 and published by the MoE. A
brief description is provided to help identify these building types. The type names are not
consistent across the country, therefore a description is given along with photos and sketches of the
most distinctive details related to these types.
A1 Two Storey Classroom Block
This type of two storey building comprises of multiple classrooms with stair wells at the rear of the
building. They have large glazed northern walls. This block was usually built with a total of 12
classrooms per block, i.e. six classrooms on each level, however could also have ten classrooms in
total. The construction type is similar to the 1950s double storey comprising a reinforced concrete
and timber infill framing.
Figure 12 : Typical drawing of a 12 Classrooms Block Double Storey structure
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A2
A3
Subfloor Framing
This type of building was considered due to the foundation details. The purpose of a subfloor
braced framing foundation is to account for slope and uneven terrain.
Figure 13 : View of Subfloor Framing CEBUS block
Figure 14 : Typical sketch of a subfloor framing structure (taken from NZS 3604:2011)
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A3
A4
Pre 1930s Two Storey Block
This type of building is generally easily identified by the date of construction. The cladding is often
brick, which was popular at the time.
Figure 15 : Pre 1930s Two storey block plan view
Figure 16 : Front facade view of a Pre 1930s Two storey block
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B1
Appendix B – Block Types by School
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Schools
Block ID
Shirley Intermediate – 60 Shirley
Road, Shirley, Chch
Wharenui Primary – 32 Matipo Street,
Riccarton, Chch
Wairakei Primary – 250 Wairakei
Street, Bryndwr, Chch
Block 1
Open Air Veranda
Block 1 & 2
Open Air Veranda
Hammersley Park Primary – 90
Quinns Road, Shirley, Chch
Heathcote Valley Primary – Bridle
Path Road. Heathcote Valley, Chch
Banks Avenue Primary – 91 Banks
Avenue, Dallington, Chch
Fendalton Open Air School – 168
Clyde Road, Fendalton, Chch
Block 1,2 & 3
Learning Centre
Hall
Block 1 (Rooms 8-14)
Block 2 (Rooms 1,2,3)
Junior Block
Blocks 3, 5, 12 and 13
(Classrooms)
Block 1 (Room 11&12)
Block 2 (Rooms 15-22)
Block 4 (Rooms 4-7)
Block 6&8 (Rooms
1,2,13,14)
Block 10 & 11 (Rooms 2327)
Block 2 (Rooms 1-6)
Block 12 (Rooms 16-17)
Thorrington Primary – 22A Colombo
Street, Lower Cashmere, Chch
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Block 1
B0
Type
Open Air Veranda
1940s Single Storey
Weatherboard
Hall with Sub-basement
under stage
Dominion Block
Open Plan Blocks
(Canterbury Education
Board)
CEBUS Mk 1 and 2
Canterbury Block
Dominion Block
Canterbury Block
CEBUS Mk 1 and 2
Prefabs – Paul Wilkin
Design
Open Plan Blocks
(Canterbury Education
Board)
CEBUS Modified (1990)
Canterbury Block
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Intensity zone
moderate
moderate
low
moderate
severe
severe
moderate
moderate
Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
Schools
Sumner Primary – 15 Colenso Street,
Sumner, Chch
Hoon Hay Primary – 91 Sparks Road,
Hoon Hay, Chch
Freeville Primary – 1 Sandy Avenue,
North New Brighton, Chch
Russley Primary – 75 Cutts Road,
Avonhead, Chch
Darfield High – 16 Ross Street,
Darfield
Heaton Intermediate – 125 Heaton
Street, Merivale, Chch
Block ID
Type
Administration/Block 1
(Rooms 11-15)
Block 19
Block 8
Block 14 & 17
Block 1-2 & 3
Canterbury Block
Learning studio 1 & 2
(Rooms 9-12)
Canterbury Block
Block 1
Canterbury Block
Paul Wilkin Design
CEBUS Mk 1 and 2
Portacom
Canterbury Block
Block 2 (Admins and rooms
9-12)
CEBUS Modified (1990)
Halls with Sub-basement
under stage
Canterbury Block
1950s Double Storey
1940s Single Storey
Weatherboard
Twelve Classroom Double
Storey Block
Manning Intermediate – 50 Hoon Hay
Road, Chch
Block 2
Branston Intermediate – 35 Amyes
Road, Hornby, Chch
Block 2
Twelve Classroom Double
Storey Block
Shirley Primary – 11 Shirley Road.
Shirley, Chch
Block 2
Open Plan Blocks
(Canterbury Education
Board)
CEBUS Mk 1
Canterbury Block
Block 10
Block 8 (Rooms 9-12)
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Intensity zone
severe
Block 12
Block 4 (Community Hall)
Block 2 & 4
Block 5
B1
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low
severe
low
severe
moderate
low
low
moderate
severe
Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
Schools
Block ID
Central New Brighton Primary – 140
Seaview Road, New Brighton, Chch
Library
Queenspark Primary – 222
Queenspark Drive, Parklands, Chch
3 of them
Middleton Grange – 50 Acacia
Avenue, Riccarton, Chch
Block B
Block K (Rooms 14-20)
Avonside Girls’ High – 180 Avonside
Drive, Chch
Block A - 1927 Brick
moderate
CEBUS Mk 1 and 2
Pre 1930s 2 Storey
Jobberns Block C
1950s Double Storey
Gresson Block B
1960s Nelson Block
straight block
Hall
Linwood North – 221 Woodham Road,
Linwood, Chch
Hall
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Open Plan Blocks
(Canterbury Education
Board)
Open Plan Blocks
(Canterbury Education
Board)
Nayland
Intensity zone
severe
Kaiapoi Borough Primary – 20 Hilton
Street, Kaiapoi
Hagley Community College – 510
Hagley Avenue, Chch
Type
low
Van Asch Deaf Education Centre – 38
Truro Street, Sumner, Chch
Burnside High – 151 Greers Road,
Burnside, Chch
B2
Halls with Sub-basement
under stage
severe
Hall without Subbasement under stage
severe
No block number
Portacom
Block G (Block D
extension)
Block B (Block E)
Nayland
Main Block
severe
low
1960s Nelson "H Block"
Pre 1930s 2 Storey Block
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moderate
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Schools
B3
Block ID
Type
Christchurch Boys’ High – Straven
Road, Riccarton, Chch
Block A (incl. library/audit
and classrooms wings)
Pre 1930s 2 Storey Block
Papanui High – 30 Langdons Road,
Papanui, Chch
Block I (Block A)
Block F (Plimsol) & Block
G or L (Library)
Block B (Hall)
Linwood College – 85 Aldwins Road,
Linwood, Chch
Cashmere High – 172 Rose Street,
Somerfield, Chch
Rangiora High – 125 East Belt,
Rangiora
Mairehau High – 440 Hills Road,
Mairehau, Chch
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1940s Single Storey
Weatherboard
1960s Nelson Straight
Block
Secondary School Hall
1950s Double Storey
Performing art Centre
Block S
Secondary School Hall
1960s Nelson "H Block"
moderate
moderate
1960s Nelson "H Block"
moderate
1950s Double Storey
1950s Double Storey
low
Tennant Block
Block F
Cartwright block
Lincoln High – 25 Boundary Road,
Lincoln
moderate
Library B1, Classroom
B1,B2, C1 & C2
Block F
Block A & B
Block C,D,E
Intensity zone
1960s Nelson "H Block"
Nelson Single Storey
Block D
1960/70s Single storey
weatherboard
1960/70s Single storey
weatherboard
Nelson Single Storey
Hall
Secondary School Hall
Block D (LHS block C)
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moderate
low
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Schools
Block ID
Shirley Boys High – 59 North Parade,
Shirley, Chch
Block F
Block E
Kaiapoi High – 101 Ohoka Road,
Kaiapoi
First stage
Second stage
Hornby High – 180 Waterloo Road,
Hornby, Chch
Block D,E,F
Avonhead Primary – 55 Avonhead
Road, Avonhead, Chch
Block 2 - Hall
B4
Type
1960/70s Single storey
weatherboard
Nelson Single Storey
S68 (Schools 1968) and
MKII in 1972
S68 (Schools 1968) and
MKII in 1972
S68 (Schools 1968) and
MKII in 1972
Intensity zone
moderate
severe
low
Hall without Subbasement under stage
low
Room 26-27
CEBUS with Subfloor
Framing
moderate
Mt Pleasant Primary – 82 Major
Hornbrook Road, Mt Pleasant, Chch
Room 9
CEBUS with Subfloor
Framing
severe
Bamford Primary – 6 Gould Crescent,
Woolston, Chch
Block 2
Dominion Block
Block 1 & 5
Dominion Block
Block 2 library
Dominion Block
St Martins Primary – 24 Albert
Terrace, St Martins, Chch
Addington Primary – 22 Brougham
Street, Addington, Chch
Bromley Primary – 33 Keighleys
Road, Bromley, Chch
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severe
moderate
severe
Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
C1
Appendix C – Building Type Performance
Summary
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C1 Open Air Veranda block
Typical photos
Observed Damage
Damage Description
Cracking in
weatherboard; sign of
frame movement.
Shirley Intermediate
Shirley Intermediate
Cracking of
foundation
Wairakei School
Wairakei School
Building #1
Liquefaction Zone
Intensity level
Rating
Shirley Intermediate
Blue
High
3
Building #2
Liquefaction Zone
Intensity level
Rating
Wharenui School
Yellow
High
2
Building #3
Liquefaction Zone
Intensity level
Rating
Wairakei School
Yellow
Low
2
C1.1 Recommendations & Conclusions
The rating of 3 for Shirley Intermediate is predominantly due to ground deformation. The connection of the
sub-floor framing to the building was assessed to be 11%NBS. Once this is addressed the building is assessed
to be greater than 34%NBS.
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C3
C2 Dominion block
Typical photos
Observed Damage
Damage Description
Rocking of Brick
Banks Avenue
Banks Avenue
Banks Avenue
Building #1
Liquefaction Zone
Intensity level
Rating
Banks Avenue
Red
High
5
Building #2
Liquefaction Zone
Intensity level
Rating
Hammersley Park
Blue
Moderate
3
C2.1 Recommendations & Conclusions
The brick veneer on the Dominion Block at Banks Avenue School had to be removed. Liquefaction caused
differential settlement at various locations. The Dominion Block has a plan irregularity (structural weakness)
due to the full length windows on one side of building. This weakness results in excessive deformation which
causes the brick veneer to become a falling hazard.
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C4
C3 Canterbury block
Typical photos
Observed Damage
Damage
Description
Minor cracking
in block veneer
Thorrington School
Sumner School
Moderate
damage to the
summerhill
stone veneer
walls. Mostly
occurs in the
concrete
masonry.
Hoon Hay School
Russley School
Building #1
Liquefaction Zone
Intensity level
Rating
Thorrington School
Yellow
High
4
Building #5
Liquefaction Zone
Intensity level
Rating
Banks Avenue
Red
High
2
Building #2
Liquefaction Zone
Intensity level
Rating
Heathcote Valley School
Yellow
Severe
1
Building #6
Liquefaction Zone
Intensity level
Rating
Russley School
Grey
Low
2
Building #3
Liquefaction Zone
Intensity level
Rating
Hoon Hay School
Yellow
High
2
Building #7
Liquefaction Zone
Intensity level
Rating
Darfield
N/A
High
3
Building #4
Liquefaction Zone
Intensity level
Rating
Freeville School
Red
Low
2
Building #8
Liquefaction Zone
Intensity level
Rating
Sumner
Yellow
Severe
1
Building #9 Central New Brighton
Liquefaction Zone
Yellow
Intensity level
Moderate
Rating
2
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C5
C3.1 Recommendations & Conclusions
The Hoon Hay School buildings (Block 1,2 & 3) were retrofited in 1989 (built in 1960) and the Thorrington
School Block 1 was built in 1957 and retrofitted in 1962. The damage to the Thorrington block is mostly due
to ground deformation.
The Canterbury Block has plan irregularity which is defined as a structural weakness. The type of
damage noted was consistent and the brick veneer became a falling hazard. These blocks have
generally performed better than the assessed capacity of 20-30%NBS, depending on the number of
adjoined blocks.
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C6
C4 12 Classrooms double storey Block
Typical photos
Observed Damage
Damage Description
Slabs not level in
various areas of the
classroom block
Manning Intermediate
Manning Intermediate
Building #1
Liquefaction Zone
Intensity level
Rating
Manning Intermediate
Yellow
Moderate
2
Building #2
Liquefaction Zone
Intensity level
Rating
Branston Intermediate School
Grey
Low
3
C4.1 Recommendations & Conclusions
The samples for this building type are in low and moderate intensity zones, and so limited conclusions can be
drawn as to this building type's seismic performance. Irregular wall layout may be a structural weakness.
This could explain the rating of 2 in a low intensity zone. Further data for other buildings of this block type in
a zone of higher ground shaking would assist in assessing the performance of this block.
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C7
C5 Open Plan Block
Typical photos
Observed Damage
Damage Description
Moderate structural
damage to the wall
and significant frame
distortion.
Lateral translation of
slab at joint with
adjoining part of
building.
Heathcote Valley School
Heathcote Valley School
Movement to wall and
ceiling linings at sheet
edge.
Queenspark School
Fendalton Open Air School
Building #1
Liquefaction Zone
Intensity level
Rating
Shirley Primary School
Blue
High
2
Building #4
Liquefaction Zone
Intensity level
Rating
Heathcote Valley
Yellow
Severe
3
Building #2
Liquefaction Zone
Intensity level
Rating
Fendalton Open air School
Blue
Moderate
2
Building #5
Liquefaction Zone
Intensity level
Rating
Queenspark School
Yellow
Low
2
Building #3
Liquefaction Zone
Intensity level
Rating
Central New Brighton
Yellow
Moderate
1
C5.1 Recommendations & Conclusions
This block has large open spaces with minimal internal bracing walls. The roof does not act as a diaphragm
and so is not effective at distributing roof loads evenly throughout the structure to the bracing walls. This
results in increased frame distortion which has caused some windows to break. The large open space,
minimal bracing, ineffective roof diaphragm resulting in increased deformation is considered to be a
structural weakness.
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C8
C6 CEBUS MK 1 & 2
Typical photos
Observed Damage
Damage Description
Pavement cracking
outside and minor
evidence of frame
distortion part of
building.
Hoon Hay School
Banks Avenue
Hoon Hay School
Building #1
Liquefaction Zone
Intensity level
Rating
Banks Avenue
Red
High
1
Building #3
Liquefaction Zone
Intensity level
Rating
Shirley Primary School
Blue
High
1
Building #2
Liquefaction Zone
Intensity level
Rating
Hoon Hay School
Yellow
High
2
Building #4
Liquefaction Zone
Intensity level
Rating
Van Asch School
Yellow
Severe
2
C6.1 Recommendations & Conclusions
CEBUS of building has a simple design with a portal frame bracing system. This type of building performed
well and no critical structural weakness has been identified. Attention should be paid to the condition of the
gangnail plates which provide the connection at the external frame connections. These have been seen to
become loose over time and become ineffective during repeated cycles of earthquake shaking.
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C9
C7 CEBUS Modified (1990)
Typical photos
Observed Damage
Damage
Description
Some ceiling panels
damaged
Russley School
Fendalton Open Air School
Building #1
Liquefaction Zone
Intensity level
Rating
Fendalton Open air School
Blue
Moderate
1
Building #2
Liquefaction Zone
Intensity level
Rating
Russley School
Grey
Low
1
C7.1 Recommendations & Conclusions
The samples for this building type are both in the lower intensity zones, limited conclusions can be drawn as
to the seismic performance of this building type. Further data for buildings in a zone of higher intensity of
ground shaking would be beneficial to their overall assessment. Both the superstructure and foundations
were assessed to be approximately 90%NBS.
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C10
C8 Prefabs - Paul Wilkin Design
Typical photos
Observed Damage
No photos taken
Damage Description
Some foundation
settlement
Sumner School
Typical timber truss system
Building #1
Liquefaction Zone
Intensity level
Rating
Banks Avenue
Red
High
2
Building #2
Liquefaction Zone
Intensity level
Rating
Sumner School
Yellow
Severe
1
C8.1 Recommendations & Conclusions
This type of building performed well, even when subjected to ground movement. The foundations were easily
re-levelled. Where necessary, the building can be lifted to enable new foundations to be constructed.
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C11
C9 Nayland Block
Typical photos
Observed Damage
No photos taken
Damage Description
Some minor cracking
Middleton Grange School
Discover School Halswell (not part
of this assessment)
Building #1
Liquefaction Zone
Intensity level
Rating
Middleton Grange School
Grey
Moderate
1
Building #2
Liquefaction Zone
Intensity level
Rating
Burnside High School
Grey
Low
2
C9.1 Recommendations & Conclusions
The samples for this building type are in the low and moderate intensity zones and so limited conclusions can
be drawn as to the seismic performance of this building type. The nearest ground shaking information
generally showed no to minor ground damage and so further data from a zone of higher intensity ground
shaking would be beneficial in the assessment of this block.
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C12
C10 Hall with Sub-basement
Typical photos
Observed Damage
xvxcxcxxczxc
Hammersley Park School
Damage Description
The hall has sustained
some minor damage,
such as hariline
cracking to a soffit
cladding panel and
minor movement of
internal GIB linings.
Russley School
Hammersley Park School
Building #1
Liquefaction Zone
Intensity level
Rating
Kaiapoi Borough School
Yellow
Moderate
2
Building #2
Liquefaction Zone
Intensity level
Rating
Russley Primary School
Grey
Low
2
Building #3
Liquefaction Zone
Intensity level
Rating
Hammersley Park School
Blue
Moderate
2
C10.1
Recommendations & Conclusions
This type of hall with a sub-basement under the stage has plan and vertical irregularity. This is a structural
weakness due to the tendency of the two sections of building to respond to the earthquake shaking
differently.
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
C13
C11 Hall without Sub-basement
Typical photos
Observed Damage
Damage Description
Moderate crack in
foundation on the
eastern side.
Foundation has
dropped.
Linwood North School
Linwood North School
Windows broken.
Linwood North School
Building #1
Liquefaction Zone
Intensity level
Rating
Avonhead School
Grey
Low
2
Building #2
Liquefaction Zone
Intensity level
Rating
Linwood North school
Blue
High
3
C11.1 Recommendations & Conclusions
This type of hall does not have any particular structural weaknesses. Primary school halls tend to be
smaller, and so roof diaphragm action and wall bracing will provide additional bracing. Lightweight cladding
materials reduce the seismic demand on the structure.
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C14
C12 Portacom
Typical photos
Observed Damage
Damage Description
Minor frame
distortion and
evidence of floor
subsidence.
Hoon Hay School
Hoon Hay School
Hoon Hay School
Building #1
Liquefaction Zone
Intensity level
Rating
Burnside High School
Grey
Low
1
Building #2
Liquefaction Zone
Intensity level
Rating
Hoon Hay School
Yellow
High
2
C12.1
Recommendations & Conclusions
This type of building performed well when subjected to ground movement, and the foundations were easily
relevelled.
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C15
C13 Subfloor Framing
Typical photos
Observed Damage
Damage Description
Out of plumb piles
under the Room 27
building. The lateral
displacement is
observed to be over
50mm.
Mt Pleasant School
St Martins School
One bearer has cracks
over the top of the
pile.
St Martins School
St Martins School
Building #1
Liquefaction Zone
Intensity level
Rating
St Martins School
Blue
High
3
Building #2
Liquefaction Zone
Intensity level
Rating
Mt Pleasant School
N/A
Severe
3
C13.1
Recommendations & Conclusions
This type of foundation performed well but has been highlighted to demonstrate the importance of
subfloor framing and its correct installation. The connection details between the foundation and
the structure are critical. If large ground deformations or intense shaking occur, the connections
could fail, resulting in movement between the structure and the foundation. Both buildings had a
combination of ground deformation and shaking.
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
C16
C14 Pre 1930s 2 Storey Block
Typical photos
Observed Damage
Damage Description
Major vertical cracks
right through the
building (around the
perimeter wall).
One masonry lintel
beam has large shear
cracks between Rm 37
and adjacent hallway
Christchurch Boys High School
Avonside Girls High School
Out of plane failure at
apex - N elevation
(masonry veneer).
Avonside Girls High School
Building #1
Liquefaction Zone
Intensity level
Rating
Building #2
Liquefaction Zone
Intensity level
Rating
Building #3
Liquefaction Zone
Intensity level
Rating
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Minor cracking to
internal plaster at
wall/ceiling joints.
Avonside Girls High School
Hagley community College
Yellow
High
2
Avonside Girl's High School
Orange
High
4
Christchurch Boys' High School
Blue
High
2
Opus International Consultants Ltd
Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
C14.1
C17
Recommendations & Conclusions
The Pre-1930s Two Storey Block at Avonside Girl's High School was retrofitted by adding
reinforced concrete walls and steel beams attached to the brick facades. Extensive damage to the
brick facade was due to ground deformation. The damage to this block at Christchurch Boys High
School was mostly due to differential settlement which made doors unable to be opened properly.
In the case of the Hagley Park Comunity Centre, the main structural weakness is the difference in
construction between the two sections of the building. In general, these buildings built in the 1930s
are likely to have critical structural weaknesses such as unreinforced brick walls that present a
falling hazard. Strengthening works carried out in the 1990s were aimed at addressing the
earthquake prone building issues which explains their relatively good performance.
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
C18
C15 1940s Single Storey Weatherboard Block
Typical photos
Observed Damage
Damage Description
Moderate structural
damage. Cracking to
ceiling, corniche and
concrete beams.
Heaton Normal Intermediate School
Heaton Normal Intermediate School
West corner of building
appears to have some
settlement under one
pile.
Wharenui school
Heaton Normal Intermediate School
Building #1
Liquefaction Zone
Intensity level
Rating
Papanui High school
Grey
Low
2
Building #2
Liquefaction Zone
Intensity level
Rating
Heaton Normal intermediate School
Blue
Moderate
3
Building #3
Liquefaction Zone
Intensity level
Rating
Wairakei School
Yellow
Low
1
C15.1
Recommendations & Conclusions
This type of one storey building performs well under seismic loads. It is a lightweight and low building.
However at Heaton Normal Intermediate, ground deformation caused significant damage to the foundation
causing cracking throughout the structure.
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
C19
C16 1950s Double Storey
Typical photos
Observed Damage
Damage Description
Severe damage to the
columns in corridor. Shear
craking just below the
beam junction.
Linwood College
Linwood College
Seismic joint opened up
and cover plate damaged
with 100mm gap between
adjacent block.
Avonside Girl’s High School
Building #1
Liquefaction Zone
Intensity level
Rating
Linwood College
Linwood College
Building #2
Blue
Liquefaction Zone
High
Intensity level
3
Rating
Rangiora High School
N/A
Low
2
Building #3
Liquefaction Zone
Intensity level
Rating
Cashmere
Yellow
High
3
Avonside Girls’ High School
Orange
High
4
C16.1
Building #4
Liquefaction Zone
Intensity level
Rating
Recommendations & Conclusions
There is insufficient bracing in the longitudinal direction due to the clerestory windows between the concrete
columns. This is a structural weakness which results in significant damage to beams and columns.
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
C20
C17 1960s Nelson Block "Straight"
Typical photos
Observed Damage
Damage Description
Separation around
frames and windows.
Avonside Girl’s High School
Avonside Girl’s High School
Avonside Girl’s High School
Avonside Girl’s High School
Building #1
Liquefaction Zone
Intensity level
Rating
Avonside Girl's High School
Orange
High
4
Building #2
Liquefaction Zone
Intensity level
Rating
Papanui High school
Grey
Low
1
C17.1
Severe liquefaction
caused differential
settlement of 50mm
approx. and lateral
spreading. The
perimeter walls settled.
Recommendations & Conclusions
One side of the building consists of two storeys of window openings with masonry veneer beneath the ground
floor windows. This plan irregularity could be a structural weakness. In addition, two structural weaknesses
found at the Avonside Girl's High School are a lack of complete diaphragm and connections to structure at 1st
floor level, and a lack of restraint to the concrete staircase in longitudinal direction. It should be noted that
the Avonside school building has had retrofitting to improve the performance of the brick walls. The
strengthening works carried out in the 1990s and 2000s aimed to address most earthquake prone building
issues which explains their relatively good performance.
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
C21
C18 1960s Nelson Block "H Plan"
Typical photos
Observed Damage
Damage Description
The school is no longer
level due to differential
settlement.
Cashmere High School
Linwood College
Building #1
Liquefaction Zone
Intensity level
Rating
Burnside High School
Grey
Low
2
Building #3
Liquefaction Zone
Intensity level
Rating
Mairehau High
Yellow
Moderate
1
Building #2
Liquefaction Zone
Intensity level
Rating
Linwood College
Blue
High
1
Building #4
Liquefaction Zone
Intensity level
Rating
Cashmere High
Yellow
High
3
C18.1
Recommendations & Conclusions
The Cashmere High school rating of 3 is mostly due to ground deformation. Burnside High school which had
not undergone much shaking but still had cracking caused by differential settlement. Otherwise, this type of
structure seems to have withstood shaking quite well. The combination of one and two storeys and different
construction materials can result in structural weaknesses. The strengthening works carried out in the 1990s
and 2000s aimed to address most structural weaknesses which explains their relatively good performance.
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
C22
C19 Nelson Single Storey
Typical photos
Observed Damage
Damage Description
Cracking and spliting
between two parts of
building
Shirley Boys High School
Shirley Boys High School
Shirley Boys High School
Building #1
Liquefaction Zone
Intensity level
Rating
Lincoln High School
N/A
High
1
Building #2
Liquefaction Zone
Intensity level
Rating
Mairehau High school
Yellow
Moderate
1
Building #3
Liquefaction Zone
Intensity level
Rating
Shirley Boys High School
Blue
High
3
C19.1
Recommendations & Conclusions
This lightweight building has generally performed well. Most of the damage recorded was due to ground
deformation. A structural weakness may be the lack of bracing between the windows.
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
C20
C23
S68 (school 68-72)
Typical photos
Observed Damage
Damage Description
Minor cracks observed
in door lintel adjacent
internal courtyard on
two-storey side of
courtyard. Masonry
block loose on left hand
side of doorway on East
courtyard elevation.
Kaiapoi High School
Kaiapoi High School
Minor cracks observed
in door lintel adjacent
internal courtyard on
two-storey side of
courtyard. Masonry
block loose on left hand
side of doorway on East
courtyard elevation.
Kaiapoi High School
Kaiapoi High School
Building #1
Liquefaction Zone
Intensity level
Rating
Kaiapoi High School
Yellow
Moderate
3
Building #2
Liquefaction Zone
Intensity level
Rating
Hornby High School
Grey
Low
1
C20.1
Recommendations & Conclusions
This one storey building has a structural weakness due to the unreinforced blockwork walls. The damage that
occurred to the Kaiapoi school building is mostly due to ground deformation.
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
C24
C21 Secondary School Hall
Typical photos
Observed Damage
Damage Description
No damage found
Cashmere High School
Building #1
Liquefaction Zone
Intensity level
Rating
Lincoln High School
N/A
High
1
Building #2
Liquefaction Zone
Intensity level
Rating
Papanui High school
Grey
Low
1
Building #3
Liquefaction Zone
Intensity level
Rating
Cashmere High School
Yellow
High
1
C21.1
Recommendations & Conclusions
The samples for this building type are in the low and moderate intensity zone, limited conclusions can
therefore be drawn as to this building type's seismic performance. Further data for other buildings of this
type in a zone of higher intensity would be beneficial.
5-C2102.00 | January 2015
Opus International Consultants Ltd
Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
D1
Appendix D – Geotechnical Description of
School Standard Blocks
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
D2
Table of Results – Geotechnical Description
Table D.1 presents the observed ground damage made available by the Canterbury Geotechnical
Database. The information presented in this database in the form of a Google Earth map is almost
entirely associated with residential properties. Therefore, the information presented is essentially a
summary of the behaviour of the residential sites surrounding the school properties.
Where no damage was observed, no entry was made in the table. In most cases where the lateral
spread at the specified school site or that of the surrounding areas has been identified, ground
cracking was also seen.
The information shown in Table D.1 below regarding the Ministry of Education Geotechnical
Classification was obtained from the Ministry of Education whilst some information was provided
from the assessments carried out by Opus Geotechnical.
Table D.1 - Schools and their respective standard blocks
School
Block Type
Ground Damage Observed
Rating
Addington Primary
Dominion
-
*
Avonhead Primary
Hall without Subbasement
-
2
Pre 1930’s 2 Storey
September
4
Lateral Spread: None to major
observed
1950’s Double Storey
Ejected liquefiable material: Often
observed
4
Avonside Girls
February
Lateral spread: Moderate to major
1960’s Nelson
“Straight”
Ejected liquefiable material: Often
observed
4
CEBUS 5
3
February
Lateral Spread: Moderate to major
Bamford Primary
Open Air Verandah
Ejected liquefiable material: Often
observed
*
Ground cracking: Minor
CEBUS 5
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Dominion
D3
1
September
Ground cracking: Minor
Canterbury
Banks Avenue Primary
CEBUS 2
Lateral spread: Severe (across the
river)
Ejected liquefiable material: Often
observed (across the river)
*
February
Prefabs
Ejected liquefiable material: Often
observed
*
Ground cracking: Minor
Paul Wilkin Design
February
Branston Intermediate
Twelve Classroom
Double Storey
No site information. Site is west of the
CBD. Closest site information
generally shows no obvious ground
damage with only small scattered
areas of :
3
Lateral spread: Moderate to major
Ejected liquefiable material: Often
observed
Bromley Primary
CEBUS 5
Open Plan
February
Ejected liquefiable material: Minor to
moderate
Nayland
Burnside High
Portacom
2
No liquefaction or lateral spread.
1960’s Nelson “H
Plan”
Cashmere High
Secondary School Hall
Canterbury
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1
2
1950’s Double Storey
1960’s Nelson “H
Plan”
*
3
February
3
Ejected liquefiable material: Minor to
moderate to the north
1
2
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
Central New Brighton Primary
Open Plan
-
1
Christchurch Boys’ High
Pre 1930’s 2 Storey
-
2
D4
February
Christchurch South Intermediate
Portacom
Ejected liquefiable material: Large
quantities
-
September
No site information. Nearby area
experienced:
Fendalton Open Air Primary
Open Plan
Ground cracking: Minor
CEBUS Modified
February
Lateral spread: Moderate to major
2
1
Ejected liquefiable material: Often
observed
February
Freeville Primary
Canterbury
Ejected liquefiable material: Large
quantity
2
February
Hagley Community College
Pre 1930’s 2 Storey
Ejected liquefiable material: Minor to
moderate
February
3
Dominion
Hammersley Park Primary
2
Lateral spread: Moderate to major
Hall with Subbasement
Ejected liquefiable material: Often
observed
2
Canterbury
1
Open Plan
3
Heathcote Valley Primary
CEBUS 2
*
CEBUS 1
*
Paul Wilkin Design
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D5
Unit Classroom
February
Heaton Normal Intermediate
1940’s Single Storey
Weatherboard
1950’s Double Storey
3
Lateral spread: Moderate to major
Ejected liquefiable material: Minor to
large
3
September
2
Canterbury
Ground cracking: Minor
CEBUS 2
Ejected liquefiable material: Minor to
moderate
Hoon Hay Primary
2
2
Portacom
February
CEBUS (various)
Ejected liquefiable material: Minor to
moderate
Hornby High
S68 (School 68-72)
No site information. Site to the west
of CBD. Closest site information
shows generally no to minor ground
damage.
2
1
September
Kaiapoi Borough Primary
Hall with Subbasement
No site information. Closest sites
experienced:

CEBUS (various)


Kaiapoi High
S68 (School 68-72)
Ground cracking: None to
minor
Lateral spread: Moderate to
major
Ejected liquefiable material:
Large quantities
2
*
-
3
-
*
CEBUS (various)
Kaiapoi North Primary
Canterbury
Lincoln High
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GC1
No site information. Site to the southwest of CBD. Closest site information
shows no to minor ground damage
observed.
1
1
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
Linwood College
D6
3
1950’s Double Storey
February
1960’s Nelson “H
Plan”
Ejected liquefiable material: Minor to
moderate
1
February
Linwood North Primary
Hall without Subbasement
Ejected liquefiable material: Large
quantities
3
Open Air Verandah
Lyttelton Main
GC2
*
Dominion
February
Mairehau High
1960’s Nelson “H
Plan”
1
Ejected liquefiable material: Minor to
moderate
1
September
Ground cracking: Minor
Manning Intermediate
Twelve Classroom
Double Storey
Ejected liquefiable material: Minor to
moderate
2
February
Ejected liquefiable material: Minor to
moderate
Middleton Grange
Nayland
No site information. Site is to west of
CBD. Closest site information shows
no to minor ground damage.
1
Mt Pleasant Primary
Subfloor Framing
-
3
1940’s Single Storey
Weatherboard
September
2
No site information but surrounding
suburbs generally experienced:
*
Ground cracking: Minor
1
Ejected liquefiable material: Minor to
moderate
*
1950’s Single Storey
CEBUS (various)
February
1930’s Nelson
“Straight”
Papanui High
Secondary School Hall
*
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Nelson Library
D7
Ejected liquefiable material: None
observed
September
Ground cracking: None observed
Ejected liquefiable material: None
observed
Queenspark Primary
Open Plan
2
February
Ground cracking: Minor
Ejected liquefiable material: Minor to
moderate
Rangiora High
1950’s Double Storey
-
2
Canterbury
2
Russley Primary
CEBUS Modified
(1990)
No site information. Site is north-west
of CBD with no to minor ground
damage.
1
2
Hall with Subbasement
September
Surrounding sites experienced no
observed damage.
Shirley Intermediate
Open Air Verandah
3
February
Ejected liquefiable material: Minor to
moderate
September
2
Shirley Primary
Open Plan
Surrounding sites experienced no
observed damage.
CEBUS 2
February
Ejected liquefiable material: Large
quantities
1
September
Shirley Boys’ High
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1960-70’s Single
Storey Weatherboard
Surrounding sites experienced no
observed damage.
3
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Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
D8
February
Lateral spread: Moderate to major
Ejected liquefiable material: Often
observed
Subfloor Framing
St Martin’s Primary
3
Open Air Verandah
*
-
CEBUS 1
*
CEBUS 4
*
Canterbury
1
Paul Wilkin Design
Sumner Primary
1
-
CEBUS (various)
*
Canterbury (modified)
*
February
Lateral spread: Moderate to major
Thorrington Primary
Canterbury Block
Ground cracking: Minor
4
Ejected liquefiable material: Large
quantities
CEBUS 2
Van Asch Deaf Education Centre
2
-
CEBUS (various)
*
September
Wairakei Primary
Open Air Verandah
No site information but adjacent areas
experienced:
1940’s Single Storey
Weatherboard
Ground cracking: Minor
2
1
Ejected liquefiable material: Minor to
moderate
Wharenui Primary
5-C2102.00 | January 2015
Open Air Verandah
Site lies to near-west of CBD which
generally experienced no to minor
ground damage.
2
Opus International Consultants Ltd
Canterbury Earthquakes – Impact on the Ministry of Education’s School Buildings
Woolston Primary
Aranui Block
CEBUS 3
D9
February
Ejected liquefiable material: Minor to
moderate
*
* These ratings are based on the DEE summary report as no primary source information is available.
5-C2102.00 | January 2015
Opus International Consultants Ltd
Opus International Consultants Ltd
20 Moorhouse Avenue
PO Box 1482, Christchurch Mail Centre,
Christchurch 8140
New Zealand
t: +64 3 363 5400
f: +64 3 365 7858
w: www.opus.co.nz