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Canterbury Earthquakes Royal Commission Te Komihana Rūwhenua o Waitaha Canterbury Earthquakes Royal Commission – Te Komihana Rūwhenua o Waitaha

Those who lost relatives and friends in the 22 February earthquake can be assured that there will be a very thorough inquiry into the failure of buildings that resulted in loss of life.
Chair, Justice Mark Cooper
 

Volume 5: Section 1: Summary and recommendations – Volumes 5–7 (Part 1)            Go to part 2  >

Final Report
Volume 5: Section 1:
Summary and recommendations -
Volumes 5-7

In these last three Volumes of our Report, we make a number of recommendations for changes to the legislation, policies and practices for the prevention or minimisation of the failure of buildings in earthquakes, on the legal and best-practice requirements for the management of buildings after earthquakes and for the design of new buildings. The numbering of the recommendations we make continues sequentially from the recommendations made in Volumes 1 to 4 of our Report.

Volume 5: Christchurch, the City and approach to this Inquiry

Section 2 of Volume 5 provides a brief history of the city of Christchurch, its buildings and its economy. It also describes the impact the Canterbury earthquakes have had on the city and its population.

In section 3 of this Volume we have set out our approach to this Inquiry, including communications with the families of those who lost their lives in building failures in the 22 February 2011 earthquake, the public hearings we conducted and the other ways in which we gathered information, investigated matters and received submissions. We have also described the way in which we managed the thousands of documents we received in the course of our Inquiry, and the reporting structure we have followed.

Volume 6: CTV building

The CTV building, designed and constructed in the mid-1980s, collapsed during the earthquake that struck Christchurch at 12:51pm on 22 February 2011. The collapse resulted in the death of 115 people and others suffered serious injuries.

Our Terms of Reference directed us to inquire into:

  • whether the building as originally designed and constructed, and as altered and maintained, complied with legal and best practice requirements;
  • whether the building was identified as earthquake-prone or was subject to any measures to make it less susceptible to earthquake-risk before 4 September 2010;
  • the nature of the land associated with the building;
  • the nature and effectiveness of assessments and remedial work after the earthquakes on 4 September and 26 December 2010;
  • why the building failed on 22 February 2011;
  • why the failure caused extensive injury and death;
  • why it differed from other buildings in the extent to which it failed; and
  • whether any particular features of the building contributed to the failure.

The Terms of Reference precluded any inquiry into questions of liability. However, this did not prevent consideration of errors or failings in design, permitting, construction, inspection or any other matter that might explain why the CTV building failed and why the failure caused such extensive injury and death.

In Volume 6 we have set out our findings on these matters. The collapse of the CTV building caused much more injury and death than any of the other building failures on 22 February 2011. Even though it was designed under relatively recent building codes, its failure was severe and resulted in the floor slabs collapsing on top of one another, leaving most of those inside the building with no chance of survival.

We do not summarise our conclusions here. Readers wanting to see a summary of those findings are directed to section 9 of Volume 6, where we set out the principal conclusions we have reached. That section was also written with a view to it being translated into the languages spoken by many of the bereaved. Unusually for a New Zealand tragedy, many of those who died were foreign nationals. Resources have not permitted the full report to be translated. However, section 9 of Volume 6 has been translated into Japanese, simplified Chinese, Thai and Korean.

The engineering design of the building was deficient in a number of respects. While there were elements of the applicable codes that were confusing, a building permit should not have been issued for the building as designed. There were also inadequacies in the construction of the building. The post-earthquake inspections of the CTV building also illustrated areas in which building assessment processes could be improved. As noted above, a summary of all our findings in respect of the CTV building is set out in section 9 of Volume 6 of this Report.

We mention here matters that are the subject of specific recommendations arising from our inquiry into the CTV building.

The CCC issued a number of permits and consents (including resource consents) for work on the CTV building between the time of its original construction and the September earthquake. In most cases, the approved work would have had no impact on the structural performance of the building in an earthquake. A penetration was cut in the floor of level 2 for installation of an internal staircase during a fit-out in 2000. We are satisfied that the penetration would not have affected the seismic performance of the building. However, in our view particular care should be taken to ensure that damage to critical reinforcing does not occur when buildings are altered.

Recommendation


We recommend that:

  1. Where holes are required to be drilled in concrete, critical reinforcing should be avoided. If it cannot be avoided, then specific mention should be made on the drawings and specifications of the process to be followed if steel is encountered, and inspection by the engineer at this critical stage should be required.

Following the earthquake, Urban Search and Rescue engineers working on the CTV site, Mr Graham Frost, Dr Robert Heywood and Mr John Trowsdale, took extensive photographs and labelled building elements. Their public-spirited initiative created an excellent record of the state of the building and individual elements following collapse. There was no formal system whereby this information was collected and the Royal Commission commends these engineers for their very thorough documentation and assessment of the collapse debris.

Overall, we consider that the evidence provided an adequate basis to make findings about the state of the building after its collapse and to draw conclusions about possible collapse scenarios. However, implementation of practice guidelines for forensic engineering is warranted to ensure that high quality forensic work is guaranteed for future investigations.

Recommendation


We recommend that:

  1. The Ministry of Business, Innovation and Employment should consider developing guidelines for structural failure investigations, including circumstances in which sites should be preserved for formal forensic examination.

It is important to identify other buildings in New Zealand that have characteristics that might lead to their collapse in a major earthquake, so that appropriate steps can be taken to reduce the potential hazard posed by these structures.

Recommendations


We recommend that:

  1. In the assessment of buildings for their potential seismic performance:
    • the individual structural elements should be examined to see if they have capacity to resist seismic and gravity load actions in an acceptably ductile manner;
    • relatively simple methods of analysis such as the equivalent static method and/or pushover analyses may be used to identify load paths through the structure and the individual structural elements for first mode type actions. The significance of local load paths associated with higher mode actions should be considered. These actions are important for the stability of parts and portions of structures and for the connection of floors to the lateral force resisting elements;
    • the load path assessment should be carried out to identify the load paths through the different structural elements and zones where strains may be concentrated, or where a load path depends on non-ductile material characteristics, such as the tensile strength of concrete or a fillet weld where the weld is the weak element;
    • while the initial lateral strength of a building may be acceptable, critical non-ductile weak links in load paths may result in rapid degradation in strength during an earthquake. It is essential to identify these characteristics and allow for this degradation in assessing potential seismic performance. The ability of a building to deform in a ductile mode and sustain its lateral strength is more important than its initial lateral strength; and
    • sophisticated analyses such as inelastic time history analyses may be carried out to further assess potential seismic performance. However, in interpreting the results of such an analysis, it is essential to allow for the approximations inherent in the analytical models of members and interactions between structural members, such as elongation, that are not analytically modelled.
  2. Arising from our study of the CTV building, it is important that the following, in particular, should be examined:
    • the beam-column joint details and the connection of beams to structural walls;
    • the connection between floors acting as diaphragms and lateral force resisting elements; and
    • the level of confinement of columns to ensure that they have adequate ductility to sustain the maximum inter-storey drifts that may be induced in a major earthquake.

In sections 8 and 9 of Volume 2 and section 6.2.5 of Volume 4 of our report we discuss other issues related to the assessment of the potential seismic performance of existing buildings.

Volume 7: Roles and responsibilities

Section 2: Building management after earthquakes

This section considers the management of buildings after an earthquake, both during and after a state of emergency. We briefly outline New Zealand’s civil defence and emergency management framework and give an overview of the building safety evaluation process used to assess buildings after an earthquake.

We consider that, overall, New Zealand was very well served by the engineers, building control officials and others who volunteered in the building safety evaluation process carried out after the Canterbury earthquakes. We appreciate the valuable evidence many of these volunteers gave the Royal Commission to assist us to make recommendations for improvements to the management of buildings after earthquakes.

The Royal Commission considers that life safety should be the main objective for managing buildings after earthquakes. We consider that current legislation provides for New Zealand’s building safety evaluation process, but we recognise that proposals to introduce new emergency management provisions into the Building Act 2004 may address some of the problems that occurred when the process transitioned from civil defence to normal building control arrangements controlled by territorial authorities.

Recommendations


We recommend that:

  1. Life safety should be the overarching objective of building management after earthquakes as communities both respond to and recover from the disaster.
  2. The building safety evaluation process should be used following a range of disasters.
  3. Legislation should provide that a building safety evaluation operation should only be commenced during a state of emergency.
  4. The Ministry of Business, Innovation and Employment should progress its proposals to incorporate new emergency risk management provisions into the Building Act 2004 to:
    • make the Ministry of Business, Innovation and Employment responsible for the development and maintenance of New Zealand’s building safety evaluation process;
    • make territorial authorities responsible for delivering a building safety evaluation operation; and
    • give the Ministry of Business, Innovation and Employment a formal role within national civil defence and emergency planning arrangements.
  5. The Ministry of Business, Innovation and Employment should continue working with the Ministry of Civil Defence and Emergency Management on the detail of the above proposals.

As well as considering the process of building safety evaluation, we have discussed and made recommendations about the way in which engineers evaluate buildings when carrying out rapid assessments and detailed engineering evaluations after earthquakes. We also make recommendations about the way that building safety evaluators should be identified and trained.

Recommendations


We recommend that:

How evaluators assess buildings after earthquakes

  1. The Ministry of Business, Innovation and Employment, the Ministry of Civil Defence and Emergency Management, GNS Science, the New Zealand Society for Earthquake Engineering and other engineering technical groups should research how and when building safety evaluators should account for aftershocks.
  2. The building safety evaluation process should set out the factors evaluators need to take into account when considering how a building will respond in an aftershock, including:
    • how close the main shock was to an urban centre that could be affected by an aftershock;
    • the direction of the main shock and any likely aftershocks; and
    • how soil, ground conditions and any other relevant factors may affect the intensity of the ground motions in an aftershock.

Mobilising a sufficient number of skilled building safety evaluators

  1. The Ministry of Business, Innovation and Employment should progress their proposal to establish a core team of building safety evaluators that the Ministry could call on.
  2. The Ministry of Business, Innovation and Employment should carefully consider the merits and detail of any proposals about the size of this group of building safety evaluators.
  3. The ability to supplement this team with more evaluators who have received basic training should be maintained.
  4. Legislation should continue to provide for a waiver of liability for building safety evaluators carrying out rapid assessments.
  5. The liability waiver for building safety evaluators should be aligned with the building safety evaluation process instead of being restricted to an operation carried out in a state of emergency.

Guidelines for building safety evaluators

  1. The Ministry of Business, Innovation and Employment should work with the New Zealand Society for Earthquake Engineering, the Structural Engineering Society New Zealand and others with appropriate experience and expertise to finalise guidelines for Detailed Engineering Evaluations as soon as possible.
  2. Guidelines should be developed that assist building safety evaluators to assess when and how to enter a damaged building.
  3. These guidelines should be based on the Urban Search and Rescue training on when and how to assess entry to a damaged building.
  4. These guidelines should be attached to the guidelines that the Ministry of Business, Innovation and Employment is developing on the way in which engineers should carry out Detailed Engineering Evaluations after earthquakes.
  5. New Zealand’s building safety evaluation guidelines should incorporate detailed guidance to engineers about the way they should assess the damage to particular building types.
  6. The field guide for building safety evaluators should be finalised.

Training for building safety evaluators

  1. The building safety evaluation process should incorporate a training programme for all building safety evaluators.
  2. Such training should cover:
    • what the building safety evaluation process is and how it works; and
    • how to identify and assess the damage evaluators observe in buildings after an earthquake.
  3. This training programme should be developed using the New Zealand Society for Earthquake Engineering’s building evaluation resource and training capability objectives framework, in which building safety evaluators are split into three different groups and each group receives a different level of training.
  4. The core group of building safety evaluators who are a national resource capable of leading a building safety evaluation operation, and those Chartered Professional Engineers, structural engineers and senior building officials who wish to be building safety evaluators, should be required to attend compulsory training.
  5. Only trained building safety evaluators should be authorised to participate in a building safety evaluation operation unless the circumstances of a particular disaster make this impractical.
  6. If the scale of the emergency requires the mobilisation of the largest group of potential building safety evaluators, who have not received the compulsory training, these evaluators should work, wherever practicable, under the supervision of those evaluators who have attended the compulsory training.
  7. Territorial authority staff with civil defence and emergency management responsibilities should be required to attend the compulsory building safety evaluator training as part of their job training.

Indicating that evaluators have the right skills

  1. The Ministry of Business, Innovation and Employment should keep a list of the people who complete the compulsory training for building safety evaluators and should make this list available to all territorial authorities.
  2. Where available, only Chartered Professional Engineers should carry out Level 2 Rapid Assessments.

Despite some problems, we consider that, overall, the building safety evaluation operations after the Canterbury earthquakes were well delivered. We recommend that a number of changes are made to improve the delivery of New Zealand’s building safety evaluation process, which follows current international best-practice.

Recommendations


We recommend that:

  1. The Indicator Building model should be incorporated into New Zealand’s building safety evaluation process.
  2. The Ministry of Business, Innovation and Employment should provide guidance to territorial authorities to support their plans to carry out a building safety evaluation process.
  3. Territorial authorities should be required to plan their building safety evaluation process as part of their civil defence and emergency management plans.
  4. Only official building safety evaluators should be authorised to place, change or remove placards, and to carry out rapid assessments for this purpose.

Recommendations related to the placards

  1. The placards placed as a result of the building safety evaluation process should be rewritten in a plain English format.
  2. In principle, the colour of the green placard should be changed to white. The Ministry of Business, Innovation and Employment should consult with the international building safety evaluation community about the merits and detail of the change before deciding whether or not to do this.
  3. Formal procedures should be developed that set out when and how the status of a building could be changed. The placard on a building should only be changed if the formal procedures are followed.

Communication and information management

  1. The Ministry of Business, Innovation and Employment should be responsible for developing and releasing public communication materials about building management after earthquakes and other disasters during and after the state of emergency.
  2. GNS Science should develop protocols and plans to ensure that it is ready to advise the Ministry of Business, Innovation and Employment, other government agencies, local authorities and the wider public after an earthquake.
  3. Information management systems should be developed as part of planning for New Zealand’s building safety evaluation process.
  4. The Ministry of Business, Innovation and Employment should work with territorial authorities and other relevant agencies to develop a way for territorial authority building records to be electronically recorded and stored off-site.
  5. A clear system for identifying individual buildings should be developed and included in the plans for a building safety evaluation process.
  6. Land Information New Zealand should continue to work on initiatives that develop consistent national addressing protocols and make this information available to the general public.

The Royal Commission heard evidence that there were significant issues in the transition of responsibility for the building safety evaluation process from civil defence to normal building management arrangements governed by territorial authorities. We discuss and make recommendations about the need for transition mechanisms and about the way in which territorial authorities should manage buildings after earthquakes. We consider that all buildings should be assessed further after the rapid assessment phase of the building safety evaluation operation. This assessment should be based on the nature of the event, the type of structure and the level of damage observed. The Royal Commission has heard evidence regarding the barriers faced by some building owners motivated to address the damage to their building after the September earthquake. We consider that some of these barriers are indicative of issues with the management of earthquake-prone buildings and we make recommendations about these specific issues in Volume 4 of our Report.

Recommendations


We recommend that:

  1. After an earthquake that has given rise to the declaration of a state of emergency, buildings should be assessed in accordance with the following process:
    • all buildings should be subject to a rapid assessment process;
    • for the purposes of subsequent steps, buildings should be placed in the following categories:
      • Group 1: non-unreinforced masonry buildings that do not have a known critical structural weakness, and either,
        • in the case of concrete buildings, were designed to NZS 3101:1995 or later editions of that Standard;
        • in the case of structural steel buildings, were designed to NZS 3404:1992 (informed by the Heavy Engineering Research Association guidelines published in 1994) or later editions of that Standard;
        or have been subject to an evaluation that has shown that the building has 67% ULS or greater (we discuss the term “ULS” in section 6.2.4 of Volume 4);
      • Group 2: buildings designed between 1976 and the mid-1990s, but not included in Group 1;
      • Group 3: buildings designed before 1976, but not included in Group 1; and
      • Group 4: unreinforced masonry buildings;
    • buildings used for residential purposes that are three or less storeys in height should be excluded from Groups 2 and 3. In the case of those buildings, a pragmatic approach needs to be taken to assessment and occupancy, which balances the need for shelter with safety considerations. Other commercial and residential buildings should not be occupied unless approved for occupancy in accordance with the process outlined below;
    • legislation should require territorial authorities to classify buildings in their districts in accordance with the preceding Recommendation within the timeframes established under Recommendation 82 in Volume 4 of our Report (Recommendation 82 requires the assessment of earthquake-prone and potentially earthquake-prone buildings);
    • where the rapid assessment process had identified the need for further evaluation of a building in one of these defined Groups, the building should not be occupied until the Civil Defence Controller or the territorial authority (as appropriate) has approved the occupancy of the building after the following assessments:
      • for Group 1 buildings:
        • where no significant structural damage was seen, a Level 2 Rapid Assessment;
        • where significant structural damage was seen, a Plans-Based Assessment for lower levels of structural damage and a Detailed Engineering Evaluation for higher levels of structural damage;
      • for Group 2 buildings:
        • where no significant structural damage was seen, a Plans-Based Assessment;
        • where significant structural damage was seen, a Detailed Engineering Evaluation;
      • for Group 3 buildings:
        • for all levels of damage, a Detailed Engineering Evaluation;
      • for Group 4 buildings:
        • where no significant structural damage was seen and the building has been retrofitted to 67% ULS or greater, a Plans-Based Assessment;
        • where significant structural damage is apparent and where the building has not been retrofitted to 67% ULS or greater, a Detailed Engineering Evaluation;
    • arranging for the Plans-Based Assessments and Detailed Engineering Evaluations should be the responsibility of the owner of the buildings concerned; and
    • the Ministry of Business, Innovation and Employment should further develop the Plans-Based Assessment concept, in consultation with the New Zealand Society for Earthquake Engineering and the Structural Engineering Society New Zealand, and set out the Plans-Based Assessment in published guidelines.
  2. Plans-Based Assessments and Detailed Engineering Evaluations should include checking the vulnerabilities observed after the Canterbury earthquakes that the Royal Commission describes in Volume 2, section 6.2.5 of Volume 4, and section 6.3.8 of Volume 6 of this Report.
  3. Any Plans-Based Assessment and Detailed Engineering Evaluation of a building after an earthquake should begin with a careful examination of the building’s plans.
  4. The Plans-Based Assessment and Detailed Engineering Evaluation should confirm that all known falling hazards and other vulnerabilities have been assessed and secured or removed.
  5. A copy of the Plans-Based Assessment and the Detailed Engineering Evaluation should be given to the relevant authorities.

Cordon management

  1. Civil defence and emergency management should be responsible for setting up and maintaining cordons during the state of emergency.
  2. Territorial authorities should be responsible for maintaining any cordons that are in place at the end of the state of emergency until the public space or building they surround is made safe.
  3. Territorial authorities should be able to recover the costs of maintaining any necessary cordons from the building owner after three months.
  4. The roles and responsibilities of decision makers should be described in the building safety evaluation process. The roles and responsibilities should allow for flexibility of operation according to the circumstances and scale of the event.

Buildings that act as one structure in an earthquake

  1. The building safety evaluation process should direct evaluators to assess properties that act as one structure in an earthquake as one structure, rather than as separate buildings.

Transition mechanism

  1. The building safety evaluation and wider building management after earthquakes (and other disasters) framework should be developed and provided for in legislation.

Volume 5: Section 1: Summary and recommendations – Volumes 5–7 (Part 1)            Go to part 2  >