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Research Papers, Lincoln University

The 2010 and 2011 earthquakes of Canterbury have had a serious and ongoing effect on Maori in the city (Lambert, Mark-Shadbolt, Ataria, & Black, 2012). Many people had to rely on themselves, their neighbours and their whanau for an extended period in 2011, and some are still required to organise and coordinate various activities such as schooling, health care, work and community activities such as church, sports and recreation in a city beset by ongoing disruption and distress. Throughout the phases of response and recovery, issues of leadership have been implicitly and explicitly woven through both formal and informal investigations and debates. This paper presents the results of a small sample of initial interviews of Maori undertaken in the response and early recovery period of the disaster and discusses some of the implications for Maori urban communities.

Audio, Radio New Zealand

A Christchurch couple in a long running dispute over the insurance payout for their earthquake damaged home have reached an out-of-court settlement with Southern Response. The class action was brought on behalf of former AMI Insurance/Southern Response policyholders who believe the company misled them into settling their claims for less than their policies entitled them to. The lawyer for Brendan and Colleen Ross, Grant Cameron, talks to Max Towle about the settlement.  

Audio, Radio New Zealand

When the 2011 Canterbury earthquakes struck, the region was hit with disaster on an unprecedented scale and the health system was challenged like never before. The injured needed immediate treatment, buildings and equipment were badly damaged, and yet those working in health system rallied to keep it going. Emergency Medicine specialist Dr Mike Ardagh and independent science writer Dr Joanne Deely have written a book, Rising from the Rubble, which tells the stories of those who were part of the health system response, and a record of the long-term issues that have been caused by it.

Audio, Radio New Zealand

Southern Response is back in court today - this time having a final go at arguing that a class action against it should not be an 'opt-out'. Christchurch residents Brendan and Colleen Ross say the state insurer deliberately withheld the true cost of repairing their home which was damaged in the Canterbury earthquakes. They are now among 3000 people represented in a class action led by Christchurch lawyer Grant Cameron. In September last year the Court of Appeal decided the class action could proceed on an 'opt-out' basis - which means it would cover more people and potentially cost the state-owned insurer more money if it loses. Southern Response is challenging that decision in the Supreme Court, a two day hearing wrapped up on Tuesday. Checkpoint reporter Logan Church was there.

Research papers, University of Canterbury Library

This dissertation addresses several fundamental and applied aspects of ground motion selection for seismic response analyses. In particular, the following topics are addressed: the theory and application of ground motion selection for scenario earthquake ruptures; the consideration of causal parameter bounds in ground motion selection; ground motion selection in the near-fault region where directivity effect is significant; and methodologies for epistemic uncertainty consideration and propagation in the context of ground motion selection and seismic performance assessment. The paragraphs below outline each contribution in more detail. A scenario-based ground motion selection method is presented which considers the joint distribution of multiple intensity measure (IM) types based on the generalised conditional intensity measure (GCIM) methodology (Bradley, 2010b, 2012c). The ground motion selection algorithm is based on generating realisations of the considered IM distributions for a specific rupture scenario and then finding the prospective ground motions which best fit the realisations using an optimal amplitude scaling factor. In addition, using different rupture scenarios and site conditions, two important aspects of the GCIM methodology are scrutinised: (i) different weight vectors for the various IMs considered; and (ii) quantifying the importance of replicate selections for ensembles with different numbers of desired ground motions. As an application of the developed scenario-based ground motion selection method, ground motion ensembles are selected to represent several major earthquake scenarios in New Zealand that pose a significant seismic hazard, namely, Alpine, Hope and Porters Pass ruptures for Christchurch city; and Wellington, Ohariu, and Wairarapa ruptures for Wellington city. A rigorous basis is developed, and sensitivity analyses performed, for the consideration of bounds on causal parameters (e.g., magnitude, source-to-site distance, and site condition) for ground motion selection. The effect of causal parameter bound selection on both the number of available prospective ground motions from an initial empirical as-recorded database, and the statistical properties of IMs of selected ground motions are examined. It is also demonstrated that using causal parameter bounds is not a reliable approach to implicitly account for ground motion duration and cumulative effects when selection is based on only spectral acceleration (SA) ordinates. Specific causal parameter bounding criteria are recommended for general use as a ‘default’ bounding criterion with possible adjustments from the analyst based on problem-specific preferences. An approach is presented to consider the forward directivity effects in seismic hazard analysis, which does not separate the hazard calculations for pulse-like and non-pulse-like ground motions. Also, the ability of ground motion selection methods to appropriately select records containing forward directivity pulse motions in the near-fault region is examined. Particular attention is given to ground motion selection which is explicitly based on ground motion IMs, including SA, duration, and cumulative measures; rather than a focus on implicit parameters (i.e., distance, and pulse or non-pulse classifications) that are conventionally used to heuristically distinguish between the near-fault and far-field records. No ad hoc criteria, in terms of the number of directivity ground motions and their pulse periods, are enforced for selecting pulse-like records. Example applications are presented with different rupture characteristics, source-to-site geometry, and site conditions. It is advocated that the selection of ground motions in the near-fault region based on IM properties alone is preferred to that in which the proportion of pulse-like motions and their pulse periods are specified a priori as strict criteria for ground motion selection. Three methods are presented to propagate the effect of seismic hazard and ground motion selection epistemic uncertainties to seismic performance metrics. These methods differ in their level of rigor considered to propagate the epistemic uncertainty in the conditional distribution of IMs utilised in ground motion selection, selected ground motion ensembles, and the number of nonlinear response history analyses performed to obtain the distribution of engineering demand parameters. These methods are compared for an example site where it is observed that, for seismic demand levels below the collapse limit, epistemic uncertainty in ground motion selection is a smaller uncertainty contributor relative to the uncertainty in the seismic hazard itself. In contrast, uncertainty in ground motion selection process increases the uncertainty in the seismic demand hazard for near-collapse demand levels.

Research papers, University of Canterbury Library

This dissertation addresses a diverse range of applied aspects in ground motion simulation validation via the response of complex structures. In particular, the following topics are addressed: (i) the investigation of similarity between recorded and simulated ground motions using code-based 3D irregular structural response analysis, (ii) the development of a framework for ground motion simulations validation to identify the cause of differences between paired observed and simulated dataset, and (iii) the illustration of the process of using simulations for seismic performance-based assessment. The application of simulated ground motions is evaluated for utilisation in engineering practice by considering responses of 3D irregular structures. Validation is performed in a code-based context when the NZS1170.5 (NZS1170.5:2004, 2004) provisions are followed for response history analysis. Two real buildings designed by engineers and physically constructed in Christchurch before the 2010-2011 Canterbury earthquake sequence are considered. The responses are compared when the buildings are subjected to 40 scaled recorded and their subsequent simulated ground motions selected from 22 February 2011 Christchurch. The similarity of recorded and simulated responses is examined using statistical methods such as bootstrapping and hypothesis testing to determine whether the differences are statistically significant. The findings demonstrate the applicability of simulated ground motion when the code-based approach is followed in response history analysis. A conceptual framework is developed to link the differences between the structural response subjected to simulated and recorded ground motions to the differences in their corresponding intensity measures. This framework allows the variability to be partitioned into the proportion that can be “explained” by the differences in ground motion intensity measures and the remaining “unexplained” variability that can be attributed to different complexities such as dynamic phasing of multi-mode response, nonlinearity, and torsion. The application of this framework is examined through a hierarchy of structures reflecting a range of complexity from single-degree-of-freedom to 3D multi-degree-of-freedom systems with different materials, dynamic properties, and structural systems. The study results suggest the areas that ground motion simulation should focus on to improve simulations by prioritising the ground motion intensity measures that most clearly account for the discrepancies in simple to complex structural responses. Three approaches are presented to consider recorded or simulated ground motions within the seismic performance-based assessment framework. Considering the applications of ground motions in hazard and response history analyses, different pathways in utilising ground motions in both areas are explored. Recorded ground motions are drawn from a global database (i.e., NGA-West2 Ancheta et al., 2014). The NZ CyberShake dataset is used to obtain simulations. Advanced ground motion selection techniques (i.e., generalized conditional intensity measure, GCIM) are used for ground motion selection at a few intensity levels. The comparison is performed by investigating the response of an example structure (i.e., 12-storey reinforced concrete special moment frame) located in South Island, NZ. Results are compared and contrasted in terms of hazard, groundmotion selection, structural responses, demand hazard, and collapse risk, then, the probable reasons for differences are discussed. The findings from this study highlight the present opportunities and shortcomings in using simulations in risk assessment. i

Images, UC QuakeStudies

A photograph of members from SPCA Canterbury meeting with Massey University's Veterinary Emergency Response Team (VERT). VERT travelled to Christchurch after the 22 February 2011 earthquake in order to assist with caring for animals.

Images, UC QuakeStudies

A photograph of members from Massey University's Veterinary Emergency Response Team (VERT) ready to depart. VERT travelled to Christchurch after the 22 February 2011 earthquake in order to assist with the caring of animals.