The 2016 Kaikoura earthquake resulted in shaking in excess of design level demands for buildings with periods of 1-2s at some locations in Wellington. This period range correlated to concrete moment frame buildings of 5-15 storeys, many of which had been built in Wellington since the early 1980s, and often with precast concrete floor units. The critical damage states used to assess buildings during the Wellington City Council Targeted Assessment Programme are described and examples of observed damage correlating to these damage states are presented. Varying degrees of beam hinging were observed, most of which are not expected to reduce the frame capacity significantly. Buildings exhibiting varying degrees of residual beam elongation were observed. Cases of significant beam elongation and associated support beam rotation resulted in damage to precast floor unit supports; in one case leading to loss of support for double-tee units. The deformation demands also resulted in damage to floor diaphragms, especially those with hollowcore floor units. Cracking in floor diaphragms was commonly concentrated in the corners of the building, but hollowcore damage was observed both at the corners and in other locations throughout several buildings. Transverse cracking of hollowcore floor units was identified as a particular concern. In some cases, transverse cracks occurred close to the support, as is consistent with previous research on hollowcore floor unit failure modes. However, transverse cracks were also observed further away from the support, which is more difficult to assess in terms of severity and residual capacity. Following the identification of typical damage, attention has shifted to assessment, repair, and retrofit strategies. Additional research may be required to determine the reduced capacity of cracked hollowcore floor units and verify commonly adopted repair and retrofit strategies.

The New Zealand Society for Earthquake Engineering (NZSEE) building safety evaluation process was implemented in several earthquakes that occurred as part of the 2010–2011 Canterbury earthquake sequence. This provided an opportunity to evaluate the effectiveness of the current processes across a range of issues. In addition to the established rapid assessments, guidelines have been developed for the detailed engineering evaluation of damaged buildings. Lessons have been drawn from these experiences relating to the effectiveness of placards and the rapid visual assessment of damage, requirements for a full spectrum of assessment processes, and training needs. Improvements to the current building safety evaluation processes are proposed and further considerations for reoccupation of damaged buildings are outlined. While this paper is based on the authors’ experiences in New Zealand, the findings are expected to have wider applications.

Professional engineers have provided a range of inputs into the responses to the Canterbury Earthquake Sequence and the recovery process that has followed. This earthquake sequence has been unique in many respects, including the intensity of shaking produced in the Christchurch CBD by each of the major aftershocks in February, June and December 2011. For engineers, the heavy workload has been continuous from the response to the original 4 September 2010 Darfield earthquake, and will extend for several years to come. There have been many post-earthquake challenges for seismologists and geotechnical and structural engineers, commencing with urban search and rescue responses and rapid building evaluations, and extending through the more detailed assessments and repair specifications during the recovery phase. Engineers are required to interface with owners, regulatory authorities and insurers, and face many challenges in meeting the objectives of these different sectors, which are rarely aligned. Adding to the technical demands has been the requirement for many scientists and engineers to provide input into the Canterbury Earthquakes Royal Commission of Inquiry and other investigations. The Royal Commission was set up to investigate the failure of buildings that led to the loss of 185 lives in the 22 February 2011 aftershock, and has placed close scrutiny on many aspects of engineering activities, particularly those undertaken following the 4 September 2010 earthquake. The prominent public reporting of the Royal Commission hearings has placed additional pressure on many engineers, including those who volunteered their services following the original earthquake into a role for which they had received only limited prior training. Interpreting and communicating ‘safety’ in relation to the re-occupancy (or continued occupancy) of commercial buildings continues to be a challenge in the face of liability concerns. A more comprehensive understanding of the technical and process guidance required by engineers and authorities has resulted from the work undertaken in response to this earthquake sequence. Much of this guidance has now been produced, and will be of considerable benefit for future major earthquake events. This paper reflects on the range of work undertaken by scientists and engineers during the response and recovery stages. The scope and implications of the various official inquiries are summarised, and the potential impacts on engineers involved in the response to and recovery from future major earthquakes are briefly discussed.

Seismic risk has traditionally been approached using probabilistic analysis. This dilutes the potential impact of low probability, extreme events that may lead to severe consequences including excessive land damage, building damage, injuries and death. The communication of risk in probabilistic terms is also not clearly understood by most audiences. Further, it is evident that few building developers, owners and users have a good understanding the implications of this and the capacity design of buildings, which may not be repairable after a severe event. There is also an adverse impact on planning and land use, where decisions that may affect many people are based on a limited view of adverse outcomes such as liquefaction, lateral spread and slope stability in severe earthquakes. A different way of thinking about seismic risk is proposed. An approach of using scenarios derived from a combination of deterministic as well as probabilistic thinking would prompt consideration of impacts over a range of events. This would allow full consideration of which outcomes are clearly not acceptable and which are. This may facilitate planning for both private and public sector, with a common understanding that is relatively easily communicated to both experts and lay people. This risk evaluation framework would also facilitate consideration of mitigation, by bringing focus on unacceptable outcomes of severe events that are currently obscured by pure probabilistic analysis. This was missing in Christchurch, which experienced the sort of event we can readily anticipate and should actively plan for in other parts of New Zealand. This would help us avoid future red zones and excessive damage and demolition. It will inform development of building codes and standards and will help us evaluate risk and provide resilience and redundancy across the range of interconnected infrastructure networks. Informed debate is needed with key decision makers to discuss the underlying objectives of our regulation and how these may be better met by such an approach, without engineers allowing themselves to be trapped in past thinking and assumptions.

The 14 November 2016 Kaikōura earthquake resulted in long duration shaking in excess of the code demand for many buildings with fundamental periods between 1 and 2 seconds in Wellington, particularly in those parts of the city where shaking has been amplified due to basin effects and deeper deposits, notably in the port area or Thorndon basin. This paper outlines the initial response of engineers and the engineering assessment processes undertaken in Wellington in the weeks following the Kaikōura Earthquake, along with the technical support provided to Wellington City Council through the establishment of the Critical Buildings Team and the Wellington Engineering Leadership Group. An overview is provided of the Targeted Assessment Programme subsequently undertaken by Wellington City Council to look more closely at the buildings most likely to be affected. Background is provided to the key elements of the Targeted Damage Evaluation Guidelines that were developed in support of this programme, including the relationship with the Detailed Engineering (Damage) Evaluation process used following the Canterbury Earthquake Sequence.