Canterbury Earthquakes Impact on the Ministry of Education s School Buildings

Transcription

1 Ministry of Education Canterbury Earthquakes Impact on the Ministry of Education s School Buildings

2 Ministry of Education Canterbury Earthquakes Impact on the Ministry of Education s School Buildings Prepared By Toby Tscherry Structural Engineer Christchurch Office 20 Moorhouse Avenue PO Box 1482, Christchurch Mail Centre, Christchurch 8140 New Zealand Reviewed By Telephone: Will Parker Facsimile: Technical Principal Earthquake Engineering & Building Structures Date: 16 January 2015 Reference: 5-C Status: Issue 10 FINAL 2015

3 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings i 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.

4 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings ii 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.

5 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings iii Contents Executive Summary... i 1 Introduction Assessment Scope Limitations Infrastructure Peak Ground Acceleration Geotechnical Potential Structural Weaknesses Selection of Buildings Considerations for Selection Selection Criteria Buildings Selected Building Type Structural Review Rating System Flowcharts and Reference Material Key Findings Summary of Building Results Discussion/Analysis of Results Conclusions General Conclusions Infrastructure Performance/Damage Block Specific Conclusions Recommendations Site Considerations Buildings and Infrastructure Process Further Review Limitations Other Site Risks 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

6 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings iv Appendix C Building Type Performance Summary... C1 C1 C2 C3 C4 C5 C6 C7 C8 C9 Open Air Veranda block... C2 C1.1 Recommendations & Conclusions... C2 Dominion block... C3 C2.1 Recommendations & Conclusions...C3 Canterbury block... C4 C3.1 Recommendations & Conclusions... C5 12 Classrooms double storey Block... C6 C4.1 Recommendations & Conclusions... C6 Open Plan Block... C7 C5.1 Recommendations & Conclusions... C7 CEBUS MK 1 & 2... C8 C6.1 Recommendations & Conclusions... C8 CEBUS Modified (1990)... C9 C7.1 Recommendations & Conclusions... C9 Prefabs - Paul Wilkin Design... C10 C8.1 Recommendations & Conclusions... C10 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

7 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings v C s Single Storey Weatherboard Block... C18 C15.1 Recommendations & Conclusions... C18 C s Double Storey... C19 C16.1 Recommendations & Conclusions... C19 C s Nelson Block "Straight"... C20 C17.1 Recommendations & Conclusions... C20 C s 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

8 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 1 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 Database 1. 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

9 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 2 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 report 2. The peak ground acceleration (PGA) in the horizontal direction closely correlates to the extent of damage caused by the earthquakes. 2 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.

10 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 3 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

11 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 4 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 R u or R s 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 /50 to 1/250 *based on new seismicity (Z=0.3)

12 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 5 Z=0.3 Figure 3: Combined Peak Ground Acceleration - Christchurch

13 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 6 Z=0.3 Figure 4: Combined Peak Ground Acceleration - Canterbury

14 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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 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.

15 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 8 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 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.

16 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 9 Figure 5: Technical Categories - Christchurch

17 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 10 Figure 6: Technical Categories - Canterbury

18 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 11 Figure 7: Full List of Ministry Schools

19 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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: 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.

20 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 13 Table 3.1: Standard Block Locations Standard Type of Building Location Primary and Intermediate Schools Shirley Intermediate 60 Shirley Road, Shirley, Chch Open Air Veranda Block Wharenui Primary 32 Matipo Street, Riccarton, Chch 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 Canterbury Block Freeville Primary 1 Sandy Avenue, North New Brighton, Chch 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

21 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 14 Standard Type of Building 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 CEBUS MK I & II Shirley Primary 11 Shirley Road, Shirley, Chch 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) Paul Wilkin Design Nayland Halls with Sub-basement under stage Hall without Sub-basement under stage Portacom Fendalton Open Air Primary 168 Clyde Road, Fendalton, Chch Russley Primary 75 Cutts Road, Avonhead, Chch Sumner Primary Colenso Street, Sumner, Chch Banks Avenue Primary 91 Banks Avenue, Dallington, Chch Middleton Grange 50 Acacia Avenue, Riccarton, Chch Burnside High 151 Greers Road, Burnside, Chch Kaiapoi Borough Primary 20 Hilton Street, Kaiapoi Russley Primary 75 Cutts Road, Avonhead, Chch Hammersley Park Primary 90 Quinns Road, Shirley, Chch Avonhead Primary 55 Avonhead Road, Avonhead, Chch Linwood North Primary 221 Woodham Road, Linwood, Chch Burnside High 151 Greers Road, Burnside, Chch

22 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 15 Standard Type of Building Location Hoon Hay Primary 91 Sparks Road, Hoon Hay, Chch Subfloor Framing St Martins Primary 24 Albert Terrace, St Martins, Chch Mt Pleasant Primary 82 Major Hornbrook Road, Chch Secondary Schools Pre 1930s 2 Storey Block Hagley Community College 510 Hagley Avenue, Addington, Chch Avonside Girls High 180 Avonside Drive, Avonside, Chch Christchurch Boys High Straven Road, Riccarton, Chch 1940 s Single Storey Weatherboard Papanui High 30 Langdons Road, Papanui, Chch Heaton Intermediate 125 Heaton Street, Merivale, Chch Wairakei Primary 250 Wairakei Street, Bryndwr, Chch Linwood College 85 Aldwins Road, Linwood, Chch 1950s Double Storey Cashmere High 172 Rose Street, Somerfield, Chch 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 Nelson Block "H Plan" Linwood College 85 Aldwins Road, Linwood, Chch 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

23 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 16 Standard Type of Building S68 (schools 1968) and MKII in 1972 Secondary school Hall Location Hornby High 180 Waterloo Road, Hornby, Chch Lincoln High 25 Boundary Road, Lincoln 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. Rating Number Table 4-1: Summary of Performance/Damage Rating System Rating Title Performance/Damage Description 1 Very Well It withstood the earthquake without any significant damage. 2 Well 3 Fair 4 Poor 5 Very Poor It withstood the earthquake with minor non-structural damage which required minor repairs prior to occupancy. It had extensive non-structural and/or minor structural damage. It needed repairs prior to usage. It had significant structural damage affecting overall structural integrity. 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 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.

24 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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

25 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 18 Figure 9: Single storey permanent classroom flowchart identification tool

26 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 19 Figure 10: Double storey classroom flowchart identification tool Figure 11: Non-classroom building flowchart identification tool

27 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 20 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 Standard block summary Building Type School Name Shaking Intensity Geotech Category Rating Comments 3,4 Open Air Veranda Block Shirley Intermediate High TC3 3 Wharenui Primary High TC2 2 Bamford Primary Severe GC2 2 * Wairakei Primary Low TC2 2 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. Dominion Block Banks Avenue Primary Hammersley Park Primary Addington Primary High Blocks 1, 2 and 4- GC4 (>500mm of lateral spread) Moderate TC3 3 High GC2 2 * 5 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). Thorrington Primary High TC2 4 Heathcote Valley Primary Severe TC2 1 Hoon Hay Primary High GC2 2 Canterbury Block Freeville Primary Low GC3 2 Banks Avenue Primary High Blocks 1, 2 and 4- GC4 (>500mm of lateral spread) Russley Primary Low TC1 2 2 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). Darfield Primary High N/A Rural and Unmapped 3 Sumner Primary Severe TC2 1 Central New Brighton Primary Moderate TC3 2 * These ratings are based on the DEE summary report as no primary source information about the damage is available. 3 Notes from standard reports and assessments by Opus and others. 4 Establishing the Resilience of Timber Framed School Buildings in New Zealand; 2014 NZSEE Conference

28 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 21 Building Type School Name Shaking Intensity Geotech Category Rating Comments 3,4 Twelve Classrooms Double Storey Manning Intermediate Branston Intermediate Moderate TC3 2 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 Open Plan Blocks Central New Brighton Primary Moderate TC3 1 Bromley Primary Severe GC2 1 * Central timber framed shear walls assessed to be 38%NBS. No structural weaknesses for the superstructure. No significant ground deformation. Heathcote Valley Primary Queenspark Primary Severe GC1/GH1 3 Low TC2 2 CEBUS 1 CEBUS 2 (MK I & II) Heathcote Valley Primary Banks Avenue Primary Hoon Hay Primary Heathcote Valley Primary Severe GC1/GH1 1 * High Blocks 1, 2 and 4- GC4 (>500mm of lateral spread) High GC2 1 * Severe GC1/GH1 1 * Shirley Primary High TC3 1 Van Asch Deaf Education Centre Severe GC1 2 1 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.

29 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 22 Building Type School Name Shaking Intensity Geotech Category Rating Comments 3,4 CEBUS Modified (1990) CEBUS 3 CEBUS 4 Paul Wilkin Design Nayland Hall with Subbasement Hall without Sub-basement Portacom 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) Sumner Primary Severe TC2 1 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. 2 Performed well subjected to ground movement. Foundations are easily relevelled. Middleton Grange Moderate TC1 1 Lower intensity zone samples. Limited conclusions can be drawn. Burnside High Low TC1 2 No significant ground deformation. Kaiapoi Borough Moderate GC3 2 Plan and vertical irregularity. This Primary may be a structural weakness due to Russley Primary Low TC1 2 the tendency of the two sections of building to respond differently. Hammersley Park Moderate TC3 2 No significant ground deformation. Primary Avonhead Primary Linwood North Primary Low TC1 2 High GC2 3 Burnside High Low TC1 1 Hoon Hay Primary High GC2 2 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.

30 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 23 Building Type School Name Shaking Intensity Geotech Category Rating Comments 3,4 Subfloor Framing Pre 1930 s 2 Storey Block St Martin s Primary Mt Pleasant Primary Hagley Community College Avonside Girls High Christchurch Boys High High Severe GH1 N/A Port Hills & Banks 3 3 The foundation/structure connection details are critical as they could fail during large ground deformation or intense shaking Peninsula High TC2 2 High GC High TC3 2 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 s Single Storey weatherboard Papanui High Low GC2 2 Heaton Normal Intermediate Moderate TC3 3 Wairakei Primary Low TC2 1 This lightweight and low building performs well under seismic loads. Ground deformation at Heaton Normal Intermediate caused significant damage to foundations and superstructure cracking s Double Storey 1960 s Nelson Block Straight Linwood College Rangiora High High Low GC3 (CPT >100mm) N/A Rural and Unmapped Cashmere High High TC3 3 Avonside Girls High School Avonside Girls High High GC2-3 4 High GC2-3. See plot provided. Papanui High Low GC2 1 3 Heavy concrete structure susceptible to ground deformation. This occurred at Linwood College and Avonside 2 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. 4 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 s 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.

31 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 24 Building Type School Name Shaking Intensity Geotech Category Rating Comments 3, s Nelson Block H Plan s Single Storey Weatherboard S68 (School 68-72) 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 Mairehau High Moderate TC2 1 Shirley Boys High High TC3 3 Kaiapoi High Moderate GC2 2 * Hornby High Low TC1 1 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 s 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.

32 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 25 Building Type School Name Shaking Intensity Geotech Category Rating 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 Lincoln High High TC1 1 Papanui High Low GC2 1 Cashmere High High TC3 1 Low and moderate intensity zone samples and no damage. No significant ground deformation. Aranui Block Woolston Primary Severe GC2 1 *S * 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).

33 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 26 Table 5-2: Performance Summary Performance/Damage Rating 1 Very Well 2 Well 3 Fair 4 Poor 5 Very Poor Severe Canterbury (2) Open Plan CEBUS 1 CEBUS 2 CEBUS 3 Paul Wilkin Aranui Open Air Veranda CEBUS 2 CEBUS 4 Subfloor Framing (unmapped) Open Plan Shaking Intensity High CEBUS 2 CEBUS 2 Single Storey WB Secondary Hall Secondary Hall Nelson H Open Air Veranda Canterbury & Canterbury Paul Wilkin Open Plan CEBUS 4 Portacom Pre Storey Pre Storey Open Air Veranda Canterbury (unmapped) Dominion Single Storey WB 1950s 2 storey (2) Nelson H Subfloor Framing Hall without SB Canterbury 1950s 2 storey Nelson Straight Dominion Pre storey Moderate Open Plan CEBUS M Nelson H Nayland Single Storey WB Canterbury Open Plan 12 Classrooms 2 storey Hall SB (2) S68 Single storey WB Dominion 12 Classrooms 2 storey Low Open Air Veranda 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)

34 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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 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 Limited 5 ; a lightweight roof improves seismic performance 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 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 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. 5 Connell Wagner Limited, Technical Guidelines for Structural Mitigation Work, July 2003 revision 7

35 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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.

36 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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.

37 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 30 6 Conclusions Due to the qualitative nature of this review, the conclusions have been separated into three categories; 6.1 General Conclusions 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 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 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.

38 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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 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 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 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

39 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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 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 Block Performance/Damage 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. 7 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.

40 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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.

41 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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.

42 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings A1 Appendix A - School Building Types

43 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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

44 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings A3 A2 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)

45 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings A4 A3 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

46 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings B1 Appendix B Block Types by School

47 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings B0 Schools Block ID Type Intensity zone Shirley Intermediate 60 Shirley Road, Shirley, Chch Wharenui Primary 32 Matipo Street, Riccarton, Chch Wairakei Primary 250 Wairakei Street, Bryndwr, Chch 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 Thorrington Primary 22A Colombo Street, Lower Cashmere, Chch Block 1 Block 1 & 2 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) Open Air Veranda Open Air Veranda 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 Block 10 & 11 (Rooms 23- Prefabs Paul Wilkin 27) Design Block 2 (Rooms 1-6) Open Plan Blocks (Canterbury Education Board) Block 12 (Rooms 16-17) CEBUS Modified (1990) Block 1 Canterbury Block moderate moderate low moderate severe severe moderate moderate

48 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings B1 Schools Block ID Type Intensity zone 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 Manning Intermediate 50 Hoon Hay Road, Chch Branston Intermediate 35 Amyes Road, Hornby, Chch Shirley Primary 11 Shirley Road. Shirley, Chch Administration/Block 1 (Rooms 11-15) Canterbury Block Block 19 Paul Wilkin Design Block 8 CEBUS Mk 1 and 2 Block 14 & 17 Portacom Block 1-2 & 3 Canterbury Block Learning studio 1 & 2 (Rooms 9-12) Block 1 Canterbury Block Canterbury Block Block 12 CEBUS Modified (1990) Block 4 (Community Hall) Halls with Sub-basement under stage Block 2 (Admins and rooms Canterbury Block 9-12) Block 2 & 4 Block 5 Block 2 Block s Double Storey 1940s Single Storey Weatherboard Twelve Classroom Double Storey Block Twelve Classroom Double Storey Block severe low severe low severe moderate Block 2 Open Plan Blocks (Canterbury Education Board) moderate Block 10 CEBUS Mk 1 Block 8 (Rooms 9-12) Canterbury Block severe low low

49 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings B2 Schools Block ID Type Intensity zone Central New Brighton Primary 140 Seaview Road, New Brighton, Chch Queenspark Primary 222 Queenspark Drive, Parklands, Chch Middleton Grange 50 Acacia Avenue, Riccarton, Chch Library Open Plan Blocks (Canterbury Education Board) 3 of them Open Plan Blocks (Canterbury Education Board) Block B Nayland moderate low Van Asch Deaf Education Centre 38 Truro Street, Sumner, Chch Block K (Rooms 14-20) CEBUS Mk 1 and 2 severe Avonside Girls High 180 Avonside Drive, Chch Block A Brick Jobberns Block C Gresson Block B Pre 1930s 2 Storey 1950s Double Storey 1960s Nelson Block straight block severe Kaiapoi Borough Primary 20 Hilton Street, Kaiapoi Hall Halls with Sub-basement under stage severe Linwood North 221 Woodham Road, Linwood, Chch Burnside High 151 Greers Road, Burnside, Chch Hall No block number Block G (Block D extension) Block B (Block E) Hall without Subbasement under stage Portacom Nayland 1960s Nelson "H Block" severe low Hagley Community College 510 Hagley Avenue, Chch Main Block Pre 1930s 2 Storey Block moderate

50 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings B3 Schools Block ID Type Intensity zone Christchurch Boys High Straven Road, Riccarton, Chch Block A (incl. library/audit and classrooms wings) Pre 1930s 2 Storey Block moderate Papanui High 30 Langdons Road, Papanui, Chch Block I (Block A) Block F (Plimsol) & Block G or L (Library) Block B (Hall) 1940s Single Storey Weatherboard 1960s Nelson Straight Block Secondary School Hall moderate Linwood College 85 Aldwins Road, Linwood, Chch Library B1, Classroom B1,B2, C1 & C2 Block F 1950s Double Storey 1960s Nelson "H Block" moderate Cashmere High 172 Rose Street, Somerfield, Chch Rangiora High 125 East Belt, Rangiora Performing art Centre Block S Block A & B Block C,D,E Secondary School Hall 1960s Nelson "H Block" 1950s Double Storey 1950s Double Storey moderate low Mairehau High 440 Hills Road, Mairehau, Chch Lincoln High 25 Boundary Road, Lincoln Tennant Block Block F Cartwright block Block D (LHS block C) Block D 1960s Nelson "H Block" Nelson Single Storey 1960/70s Single storey weatherboard 1960/70s Single storey weatherboard Nelson Single Storey moderate low Hall Secondary School Hall

51 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings B4 Schools Block ID Type Intensity zone Shirley Boys High 59 North Parade, Shirley, Chch Kaiapoi High 101 Ohoka Road, Kaiapoi Hornby High 180 Waterloo Road, Hornby, Chch Block F Block E First stage Second stage Block D,E,F 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 moderate severe low Avonhead Primary 55 Avonhead Road, Avonhead, Chch Block 2 - Hall Hall without Subbasement under stage low St Martins Primary 24 Albert Terrace, St Martins, Chch Room 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 severe Addington Primary 22 Brougham Street, Addington, Chch Block 1 & 5 Dominion Block moderate Bromley Primary 33 Keighleys Road, Bromley, Chch Block 2 library Dominion Block severe

52 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C1 Appendix C Building Type Performance Summary

53 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C2 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 Shirley Intermediate Liquefaction Zone Blue Intensity level High Rating 3 Building #2 Wharenui School Liquefaction Zone Yellow Intensity level High Rating 2 Building #3 Wairakei School Liquefaction Zone Yellow Intensity level Low Rating 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.

54 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C3 C2 Dominion block Typical photos Observed Damage Damage Description Rocking of Brick Banks Avenue Banks Avenue Banks Avenue Building #1 Banks Avenue Liquefaction Zone Red Intensity level High Rating 5 Building #2 Hammersley Park Liquefaction Zone Blue Intensity level Moderate Rating 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.

55 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C4 C3 Canterbury block Typical photos Observed Damage Damage Description Minor cracking in block veneer Sumner School Thorrington School Moderate damage to the summerhill stone veneer walls. Mostly occurs in the concrete masonry. Hoon Hay School Russley School Building #1 Thorrington School Building #5 Banks Avenue Liquefaction Zone Yellow Liquefaction Zone Red Intensity level High Intensity level High Rating 4 Rating 2 Building #2 Heathcote Valley School Building #6 Russley School Liquefaction Zone Yellow Liquefaction Zone Grey Intensity level Severe Intensity level Low Rating 1 Rating 2 Building #3 Hoon Hay School Building #7 Darfield Liquefaction Zone Yellow Liquefaction Zone N/A Intensity level High Intensity level High Rating 2 Rating 3 Building #4 Freeville School Building #8 Sumner Liquefaction Zone Red Liquefaction Zone Yellow Intensity level Low Intensity level Severe Rating 2 Rating 1 Building #9 Central New Brighton Liquefaction Zone Yellow Intensity level Moderate Rating 2

56 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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 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.

57 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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 Building #1 Manning Intermediate Liquefaction Zone Yellow Intensity level Moderate Rating 2 Manning Intermediate Building #2 Branston Intermediate School Liquefaction Zone Grey Intensity level Low Rating 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.

58 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C7 C5 Open Plan Block Typical photos Observed Damage Damage Description Moderate structural damage to the wall and significant frame distortion. Heathcote Valley School Lateral translation of slab at joint with adjoining part of building. Heathcote Valley School Movement to wall and ceiling linings at sheet edge. Queenspark School Fendalton Open Air School Building #1 Shirley Primary School Building #4 Heathcote Valley Liquefaction Zone Blue Liquefaction Zone Yellow Intensity level High Intensity level Severe Rating 2 Rating 3 Building #2 Fendalton Open air School Building #5 Queenspark School Liquefaction Zone Blue Liquefaction Zone Yellow Intensity level Moderate Intensity level Low Rating 2 Rating 2 Building #3 Central New Brighton Liquefaction Zone Yellow Intensity level Moderate Rating 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.

59 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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 Banks Avenue Building #3 Shirley Primary School Liquefaction Zone Red Liquefaction Zone Blue Intensity level High Intensity level High Rating 1 Rating 1 Building #2 Hoon Hay School Building #4 Van Asch School Liquefaction Zone Yellow Liquefaction Zone Yellow Intensity level High Intensity level Severe Rating 2 Rating 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.

60 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C9 C7 CEBUS Modified (1990) Typical photos Observed Damage Damage Description Some ceiling panels damaged Russley School Fendalton Open Air School Building #1 Fendalton Open air School Liquefaction Zone Blue Intensity level Moderate Rating 1 Building #2 Russley School Liquefaction Zone Grey Intensity level Low Rating 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.

61 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C10 C8 Prefabs - Paul Wilkin Design Typical photos Observed Damage Damage Description No photos taken Some foundation settlement Sumner School Typical timber truss system Building #1 Banks Avenue Liquefaction Zone Red Intensity level High Rating 2 Building #2 Sumner School Liquefaction Zone Yellow Intensity level Severe Rating 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.

62 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C11 C9 Nayland Block Typical photos Observed Damage Damage Description No photos taken Some minor cracking Middleton Grange School Discover School Halswell (not part of this assessment) Building #1 Middleton Grange School Liquefaction Zone Grey Intensity level Moderate Rating 1 Building #2 Burnside High School Liquefaction Zone Grey Intensity level Low Rating 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.

63 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C12 C10 Hall with Sub-basement Typical photos Observed Damage Damage Description xvxcxcxxczxc The hall has sustained some minor damage, such as hariline cracking to a soffit cladding panel and Hammersley Park School minor movement of internal GIB linings. Hammersley Park School Russley School Building #1 Kaiapoi Borough School Liquefaction Zone Yellow Intensity level Moderate Rating 2 Building #2 Russley Primary School Liquefaction Zone Grey Intensity level Low Rating 2 Building #3 Hammersley Park School Liquefaction Zone Blue Intensity level Moderate Rating 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.

64 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. Building #1 Avonhead School Liquefaction Zone Grey Intensity level Low Rating 2 Building #2 Linwood North school Liquefaction Zone Blue Intensity level High Rating 3 Linwood North School 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.

65 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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 Burnside High School Liquefaction Zone Grey Intensity level Low Rating 1 Building #2 Hoon Hay School Liquefaction Zone Yellow Intensity level High Rating 2 C12.1 Recommendations & Conclusions This type of building performed well when subjected to ground movement, and the foundations were easily relevelled.

66 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings 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 Building #1 St Martins School Liquefaction Zone Blue Intensity level High Rating 3 Building #2 Mt Pleasant School Liquefaction Zone N/A Intensity level Severe Rating 3 St Martins School 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.

67 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). Christchurch Boys High School One masonry lintel beam has large shear cracks between Rm 37 and adjacent hallway Avonside Girls High School Out of plane failure at apex - N elevation (masonry veneer). Avonside Girls High School Minor cracking to internal plaster at wall/ceiling joints. Avonside Girls High School Building #1 Hagley community College Liquefaction Zone Yellow Intensity level High Rating 2 Building #2 Avonside Girl's High School Liquefaction Zone Orange Intensity level High Rating 4 Building #3 Christchurch Boys' High School Liquefaction Zone Blue Intensity level High Rating 2

68 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C17 C14.1 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.

69 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C18 C s 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 Papanui High school Liquefaction Zone Grey Intensity level Low Rating 2 Building #2 Heaton Normal intermediate School Liquefaction Zone Blue Intensity level Moderate Rating 3 Building #3 Wairakei School Liquefaction Zone Yellow Intensity level Low Rating 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.

70 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C19 C s 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 Linwood College Building #1 Linwood College Building #2 Rangiora High School Liquefaction Zone Blue Liquefaction Zone N/A Intensity level High Intensity level Low Rating 3 Rating 2 Building #3 Cashmere Building #4 Avonside Girls High School Liquefaction Zone Yellow Liquefaction Zone Orange Intensity level High Intensity level High Rating 3 Rating 4 C16.1 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.

71 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C20 C s Nelson Block "Straight" Typical photos Observed Damage Damage Description Separation around frames and windows. Avonside Girl s High School Avonside Girl s High School Severe liquefaction caused differential settlement of 50mm approx. and lateral spreading. The perimeter walls settled. Avonside Girl s High School Avonside Girl s High School Building #1 Avonside Girl's High School Liquefaction Zone Orange Intensity level High Rating 4 Building #2 Papanui High school Liquefaction Zone Grey Intensity level Low Rating 1 C17.1 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.

72 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C21 C s Nelson Block "H Plan" Typical photos Observed Damage Damage Description The school is no longer level due to differential settlement. Linwood College Cashmere High School Building #1 Burnside High School Building #3 Mairehau High Liquefaction Zone Grey Liquefaction Zone Yellow Intensity level Low Intensity level Moderate Rating 2 Rating 1 Building #2 Linwood College Building #4 Cashmere High Liquefaction Zone Blue Liquefaction Zone Yellow Intensity level High Intensity level High Rating 1 Rating 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.

73 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 Lincoln High School Liquefaction Zone N/A Intensity level High Rating 1 Building #2 Mairehau High school Liquefaction Zone Yellow Intensity level Moderate Rating 1 Building #3 Shirley Boys High School Liquefaction Zone Blue Intensity level High Rating 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.

74 Canterbury Earthquakes Impact on the Ministry of Education s School Buildings C23 C20 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 Kaiapoi High School Liquefaction Zone Yellow Intensity level Moderate Rating 3 Building #2 Hornby High School Liquefaction Zone Grey Intensity level Low Rating 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.

75 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 Lincoln High School Liquefaction Zone N/A Intensity level High Rating 1 Building #2 Papanui High school Liquefaction Zone Grey Intensity level Low Rating 1 Building #3 Cashmere High School Liquefaction Zone Yellow Intensity level High Rating 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.