Recently developed performance-based earthquake engineering framework, such as one provided by PEER (Deierlein et al. 2003), assist in the quantification in terms of performance such as casualty, monetary losses and downtime. This opens up the opportunity to identify cost-effective retrofit/rehabilitation strategies by comparing upfront costs associated with retrofit with the repair costs that can be expected over time. This loss assessment can be strengthened by learning from recent earthquakes, such as the 2010 Canterbury and 2016 Kaikoura earthquakes. In order to investigate which types of retrofit/rehabilitation strategies may be most cost-effective, a case study building was chosen for this research. The Pacific Tower, a 22-storey EBF apartment located within the Christchurch central business district (CBD), was damaged and repaired during the 2010 Canterbury earthquake series. As such, by taking hazard levels accordingly (i.e. to correspond to the Christchurch CBD), modelling and analysing the structure, and considering the vulnerability and repair costs of its different components, it is possible to predict the expected losses of the aforementioned building. Using this information, cost-effective retrofit/rehabilitation strategy can be determined. This research found that more often than not, it would be beneficial to improve the performance of valuable non-structural components, such as partitions. Although it is true that improving such elements will increase the initial costs, over time, the benefits gained from reduced losses should be expected to overcome the initial costs. Aftershocks do increase the predicted losses of a building even in lower intensities due to the fact that non-structural components can get damaged at such low intensities. By comparing losses computed with and without consideration of aftershocks for a range of historical earthquakes, it was found that the ratio between losses due to main shock with aftershocks to the losses due to the main shock only tended to increase with increasing main shock magnitude. This may be due to the fact that larger magnitude earthquakes tend to generate larger magnitude aftershocks and as those aftershocks happen within a region around the main shock, they are more likely to cause intense shaking and additional damage. In addition to this observation, it was observed that the most significant component of loss of the case study building was the non-structural partition walls.
© 2017 The Royal Society of New Zealand. This paper discusses simulated ground motion intensity, and its underlying modelling assumptions, for great earthquakes on the Alpine Fault. The simulations utilise the latest understanding of wave propagation physics, kinematic earthquake rupture descriptions and the three-dimensional nature of the Earth's crust in the South Island of New Zealand. The effect of hypocentre location is explicitly examined, which is found to lead to significant differences in ground motion intensities (quantified in the form of peak ground velocity, PGV) over the northern half and southwest of the South Island. Comparison with previously adopted empirical ground motion models also illustrates that the simulations, which explicitly model rupture directivity and basin-generated surface waves, lead to notably larger PGV amplitudes than the empirical predictions in the northern half of the South Island and Canterbury. The simulations performed in this paper have been adopted, as one possible ground motion prediction, in the ‘Project AF8’ Civil Defence Emergency Management exercise scenario. The similarity of the modelled ground motion features with those observed in recent worldwide earthquakes as well as similar simulations in other regions, and the notably higher simulated amplitudes than those from empirical predictions, may warrant a re-examination of regional impact assessments for major Alpine Fault earthquakes.
Research in the governance of urban tourist spaces is characterized by a lack of argumentative inquiry and scant use of critical theory. This is evident, particularly, in the study of tourism and post-disaster urban recovery, with very few contributions assessing the phenomenon from a social theory perspective. This thesis examines the complex phenomenon of planning and governance for urban tourism spaces in contexts facing physical recovery from natural disasters. It does so by looking at the governance dynamics and the mechanism of decision- making put in place before and after triggering events like earthquakes and tsunamis. This thesis provides evidence from Christchurch, New Zealand, by focusing on the policies and strategies for the regeneration of the city centre put in place before and after the disruptive earthquakes of 2010 and 2011. The thesis looks at power relations, structures and ideologies through a Lukesian appraisal of pre-and-post disaster governance from two relevant urban tourist spaces located in the Christchurch central city area: the Arts Centre of Christchurch and the Town Hall and Performing Arts Precinct. The research strategy adopted for the study combined archival research, interviews with key stakeholders and fieldwork notes over a period of two years. The research deployed a comparative case study methodology that focuses on projects taking place within a spatially defined area of the city centre where special legislation was enacted as result of the earthquakes. The findings from the interviews and their triangulation with documents retrieved from national and local authorities suggest that the earthquakes affected the engagement among stakeholders and the mechanisms of decision-making. Also, the findings show patterns of disaster capitalism in post-earthquake governance for urban tourist spaces in the Christchurch CBD, with episodes of exclusion, lobbying and amendment of rules and legislation that directly benefited the interests of a narrow group of privileged stakeholders. Overall, the study shows that the earthquakes of 2010 and 2011 accelerated neoliberal practices of site development in Christchurch, with the seismic events used as a pretext to implement market-oriented site projects in the CBD area.
Decision making on the reinstatement of the Christchurch sewer system after the Canterbury (New Zealand) earthquake sequence in 2010–2011 relied strongly on damage data, in particular closed circuit television (CCTV). This paper documents that process and considers how data can influence decision making. Data are analyzed on 33,000 pipes and 13,000 repairs and renewals. The primary findings are that (1) there should be a threshold of damage per pipe set to make efficient use of CCTV; (2) for those who are estimating potential damage, care must be taken in direct use of repair data without an understanding of the actual damage modes; and (3) a strong correlation was found between the ratio of faults to repairs per pipe and the estimated peak ground velocity. Taken together, the results provide evidence of the extra benefit that damage data can provide over repair data for wastewater networks and may help guide others in the development of appropriate strategies for data collection and wastewater pipe decisions after disasters.
The 2010–2011 Canterbury earthquakes, which involved widespread damage during the February 2011 event and ongoing aftershocks near the Christchurch Central Business District, left this community with more than $NZD 40 billion in losses (~20 % GDP), demolition of approximately 60 % of multi-storey concrete buildings (3 storeys and up), and closure of the core business district for over 2 years. The aftermath of the earthquake sequence has revealed unique issues and complexities for the owners of commercial and multi-storey residential buildings in relation to unexpected technical, legal, and financial challenges when making decisions regarding the future of their buildings impacted by the earthquakes. The paper presents a framework to understand the factors influencing post-earthquake decisions (repair or demolish) on multi-storey concrete buildings in Christchurch. The study, conducted in 2014, includes in-depth investigations on 15 case-study buildings using 27 semi-structured interviews with various property owners, property managers, insurers, engineers, and government authorities in New Zealand. The interviews revealed insights regarding the multitude of factors influencing post-earthquake decisions and losses. As expected, the level of damage and repairability (cost to repair) generally dictated the course of action. There is strong evidence, however, that other variables have significantly influenced the decision on a number of buildings, such as insurance, business strategies, perception of risks, building regulations (and compliance costs), and government decisions. The decision-making process for each building is complex and unique, not solely driven by structural damage. Furthermore, the findings have put the spotlight on insurance policy wordings and the paradoxical effect of insurance on the recovery of Christchurch, leading to other challenges and issues going forward.
This research attempts to understand whether community resilience and perceived livability are influenced by housing typologies in Christchurch, New Zealand. Using recent resident surveys undertaken by the Christchurch City Council, two indexes were created to reflect livability and community resilience. Indicators used to create both indexes included (1) enjoyment living in neighbourhood (2) satisfaction with local facilities (3) safety walking and (4) safety using public transport, (5) sense of community (6) neighbour interactions, (7) home ownership and (8) civic engagement. Scores were attributed to 72 neighbourhoods across Christchurch –and each neighbourhood was classified in one of the following housing typologies; (1) earthquake damaged, (2) relatively undamaged, (3) medium density and (4) greenfield developments. Spatial analysis of index scores and housing classifications suggest housing typologies do influence resident’s perceived livability and community bonds to an extent. It was found that deprivation also had a considerable influence on these indexes as well as residential stability. These additional influences help explain why neighbourhoods within the same housing classification differ in their index scores. Based on these results, several recommendations have been made to the CCC in relation to future research, urban development strategies and suburb specific renewal projects. Of chief importance, medium density neighbourhoods and deprived neighbourhoods require conscious efforts to foster community resilience. Results indicate that community resilience might be more important than livability in having a positive influence on the lived experience of residents. While thoughtful design and planning are important, this research suggests geospatial research tools could enable better community engagement outcomes and planning outcomes, and this could be interwoven into proactive and inclusive planning approaches like placemaking.
Five years on from the 2010-2011 Canterbury earthquakes, research has shown an increase in hyperarousal symptoms in school children. While Cognitive Behaviour Therapy is currently the gold standard for treating Post-Traumatic Stress, there are insufficient clinicians to treat the high numbers of children in post-disaster communities. Alternative non-verbal interventions in school based settings that target the physiological basis of hyperarousal may be more effective for long term stress reduction in some young children. Neuroscience research suggests that drawing activates brain areas connected with the autonomic nervous system, resulting in relaxation and self-regulation. The aim of the current study was to determine whether a 20-minute drawing lesson during the afternoon of the school day would reduce stress in children with hyperarousal symptoms. The study had a single subject ABA design. Four children participated, two of the children exhibited hyperarousal symptoms, and the other two did not, as determined by teacher and parent responses on the Behaviour Problem Index (BPI). The children’s selfreported stress (measured by the Subjective Unit of Distress (SUD) thermometer) and physiological stress (measured by finger temperature) were recorded at the start and end of each session during baseline, drawing lessons, and return to baseline phases. The results of the study showed a general reduction in physiological stress during the drawing lessons for the children with hyperarousal symptoms. However, the results indicated some discrepancies between the children’s physiological stress and perception of stress, which may suggest that the self-report measure was inappropriate for the children in this study. Overall, the study suggests that drawing lessons show promise as a school-based intervention for reducing stress in children with hyperarousal. More research is required to address the limitations of the present study, and before the study can be applied to the whole classroom as a positive strategy for managing stress at school.
This report presents the simplified seismic assessment of a case study reinforced concrete (RC) building following the newly developed and refined NZSEE/MBIE guidelines on seismic assessment (NZSEE/MBIE, semi-final draft 26 October 2016). After an overview of the step-by-step ‘diagnostic’ process, including an holistic and qualitative description of the expected vulnerabilities and of the assessment strategy/methodology, focus is given, whilst not limited, to the implementation of a Detailed Seismic Assessment (DSA) (NZSEE/MBIE, 2016c). The DSA is intended to provide a more reliable and consistent outcome than what can be provided by an initial seismic assessment (ISA). In fact, while the Initial Seismic Assessment (ISA), of which the Initial Evaluation Procedure is only a part of, is the more natural and still recommended first step in the overall assessment process, it is mostly intended to be a coarse evaluation involving as few resources as reasonably possible. It is thus expected that an ISA will be followed by a Detailed Seismic Assessment (DSA) not only where the threshold of 33%NBS is not achieved but also where important decisions are intended that are reliant on the seismic status of the building. The use of %NBS (% New Building Standard) as a capacity/demand ratio to describe the result of the seismic assessment at all levels of assessment procedure (ISA through to DSA) is deliberate by the NZSEE/MBIE guidelines (Part A) (NZSEE/MBIE 2016a). The rating for the building needs only be based on the lowest level of assessment that is warranted for the particular circumstances. Discussion on how the %NBS rating is to be determined can be found in Section A3.3 (NZSEE/MBIE 2016a), and, more specifically, in Part B for the ISA (NZSEE/MBIE 2016b) and Part C for the DSA (NZSEE/MBIE 2016c). As per other international approaches, the DSA can be based on several analysis procedures to assess the structural behaviour (linear, nonlinear, static or dynamic, force or displacement-based). The significantly revamped NZSEE 2016 Seismic Assessment Guidelines strongly recommend the use of an analytical (basically ‘by hand’) method, referred to the Simple Lateral Mechanism Analysis (SLaMA) as a first phase of any other numerically-based analysis method. Significant effort has thus been dedicated to provide within the NZSEE 2016 guidelines (NZSEE/MBIE 2016c) a step-by-step description of the procedure, either in general terms (Chapter 2) or with specific reference to Reinforced Concrete Buildings (Chapter 5). More specifically, extract from the guidelines, NZSEE “recommend using the Simple Lateral Mechanism Analysis (SLaMA) procedure as a first step in any assessment. While SLaMA is essentially an analysis technique, it enables assessors to investigate (and present in a simple form) the potential contribution and interaction of a number of structural elements and their likely effect on the building’s global capacity. In some cases, the results of a SLaMA will only be indicative. However, it is expected that its use should help assessors achieve a more reliable outcome than if they only carried out a detailed analysis, especially if that analysis is limited to the elastic range For complex structural systems, a 3D dynamic analysis may be necessary to supplement the simplified nonlinear Simple Lateral Mechanism Analysis (SLaMA).” This report presents the development of a full design example for the the implementation of the SLaMA method on a case study buildings and a validation/comparison with a non-linear static (pushover) analysis. The step-by-step-procedure, summarized in Figure 1, will be herein demonstrated from a component level (beams, columns, wall elements) to a subassembly level (hierarchy of strength in a beam-column joint) and to a system level (frame, C-Wall) assuming initially a 2D behaviour of the key structural system, and then incorporating a by-hand 3D behaviour (torsional effects).
Background The 2010/2011 Canterbury earthquakes and aftershocks in New Zealand caused unprecedented destruction to the physical, social, economic, and community fabric of Christchurch city. The recovery phase in Christchurch is on going, six years following the initial earthquake. Research exploring how disabled populations experience community inclusion in the longer-term recovery following natural disasters is scant. Yet such information is vital to ensure that recovering communities are inclusive for all members of the affected population. This thesis specifically examined how people who use wheelchairs experienced community inclusion four years following the 2010/2011 Canterbury earthquakes. Aims The primary research aim was to understand how one section of the disability community – people who use wheelchairs – experienced community inclusion over the four years following the 2010/2011 Canterbury earthquakes and aftershocks. A secondary aim was to test a novel sampling approach, Respondent Driven Sampling, which had the potential to enable unbiased population-based estimates. This was motivated by the lack of an available sampling frame for the target population, which would inhibit recruitment of a representative sample. Methodology and methods An exploratory sequential mixed methods design was used, beginning with a qualitative phase (Phase One), which informed a second quantitative phase (Phase Two). The qualitative phase had two stages. First, a small sample of people who use wheelchairs participated in an individual, semi-structured interview. In the second stage, these participants were then invited to a group interview to clarify and prioritise themes identified in the individual interviews. The quantitative phase was a cross-sectional survey developed from the findings from Phase One. Initially, Respondent Driven Sampling was employed to conduct a national, electronic cross-sectional survey that aimed to recruit a sample that may provide unbiased population-based estimates. Following the unsuccessful application of Respondent Driven Sampling, a region-specific convenience sampling approach was used. The datasets from the qualitative and quantitative phases were integrated to address the primary aim of the research. Results In Phase One 13 participants completed the individual interviews, and five of them contributed to the group interview. Thematic analysis of individual and group interview data suggested that participants felt the 2010/11 earthquakes magnified many pre-existing barriers to community inclusion, and also created an exciting opportunity for change. This finding was encapsulated in five themes: 1) earthquakes magnified barriers, 2) community inclusion requires energy, 3) social connections are important, 4) an opportunity lost, and 5) an opportunity found. The findings from Phase One informed the development of a survey instrument to investigate how these findings generalised to a larger sample of individuals who use wheelchairs. In Phase Two, the Respondent Driven Sampling approach failed to recruit enough participants to satisfy the statistical requirements needed to reach equilibrium, thereby enabling the calculation of unbiased population estimates. The subsequent convenience sampling approach recruited 49 participants who, combined with the 15 participants from the Respondent Driven Sampling approach that remained eligible for the region-specific sample, resulted in the total of 64 individuals who used wheelchairs and were residents of Christchurch. Participants reported their level of community inclusion at three time periods: the six months prior to the first earthquake in September 2010 (time one), the six months following the first earthquake in September 2010 (time two), and the six months prior to survey completion (between October 2015 and March 2016, (time three)). Survey data provided some precision regarding the timing in which the magnified barriers developed. Difficulty with community inclusion rose significantly between time one and time two, and while reducing slightly, was still present during time three, and had not returned to the time one baseline. The integrated findings from Phase One and Phase Two suggested that magnified barriers to community inclusion had been sustained four years post-earthquake, and community access had not returned to pre-earthquake levels, let alone improved beyond pre-earthquake levels. Conclusion Findings from this mixed methods study suggest that four years following the initial earthquake, participants were still experiencing multiple magnified barriers, which contributed to physical and social exclusion, as well as fatigue, as participants relied on individual agency to negotiate such barriers. Participants also highlighted the exciting opportunity to create an accessible city. However because they were still experiencing barriers four years following the initial event, and were concerned that this opportunity might be lost if the recovery proceeds without commitment and awareness from the numerous stakeholders involved in guiding the recovery. To truly realise the opportunity to create an accessible city following a disaster, the transition from the response phase to a sustainable longer-term recovery must adopt a new model of community engagement where decision-makers partner with people living with disability to co-produce a vision and strategy for creating an inclusive community. Furthermore, despite the unsuccessful use of Respondent Driven Sampling in this study, future research exploring the application of RDS with wheelchair users is recommended before discounting this sampling approach in this population.
Non-structural elements (NSEs) have frequently proven to contribute to significant losses sustained from earthquakes in the form of damage, downtime, injury and death. In New Zealand (NZ), the 2010 and 2011 Canterbury Earthquake Sequence (CES), the 2013 Seddon and Cook Strait earthquake sequence and the 2016 Kaikoura earthquake were major milestones in this regard as significant damage to building NSEs both highlighted and further reinforced the importance of NSE seismic performance to the resilience of urban centres. Extensive damage in suspended ceilings, partition walls, façades and building services following the CES was reported to be partly due to erroneous seismic design or installation or caused by intervening elements. Moreover, the low-damage solutions developed for structural systems sometimes allow for relatively large inter-story drifts -compared to conventional designs- which may not have been considered in the seismic design of NSEs. Having observed these shortcomings, this study on suspended ceilings was carried out with five main goals: i) Understanding the seismic performance of the system commonly used in NZ; ii) Understanding the transfer of seismic design actions through different suspended ceiling components, iii) Investigating potential low-damage solutions; iii) Evaluating the compatibility of the current ceiling system with other low-damage NSEs; and iv) Investigating the application of numerical analysis to simulate the response of ceiling systems. The first phase of the study followed a joint research work between the University of Canterbury (UC) in NZ, and the Politecnico Di Milano, in Italy. The experimental ceiling component fragility curves obtained in this existing study were employed to produce analytical fragility curves for a perimeter-fixed ceiling of a given size and weight, with grid acceleration as the intensity measure. The validity of the method was proven through comparisons between this proposed analytical approach with the recommended procedures in proprietary products design guidelines, as well as experimental fragility curves from other studies. For application to engineering design practice, and using fragility curves for a range of ceiling lengths and weights, design curves were produced for estimating the allowable grid lengths for a given demand level. In the second phase of this study, three specimens of perimeter-fixed ceilings were tested on a shake table under both sinusoidal and random floor motion input. The experiments considered the relationship between the floor acceleration, acceleration of the ceiling grid, the axial force induced in the grid members, and the effect of boundary conditions on the transfer of these axial forces. A direct correlation was observed between the axial force (recorded via load cells) and the horizontal acceleration measured on the ceiling grid. Moreover, the amplification of floor acceleration, as transferred through ceiling components, was examined and found (in several tests) to be greater than the recommended factor for the design of ceilings provided in the NZ earthquake loadings standard NZS1170.5. However, this amplification was found to be influenced by the pounding interactions between the ceiling grid members and the tiles, and this amplification diminished considerably when the high frequency content was filtered out from the output time histories. The experiments ended with damage in the ceiling grid connection at an axial force similar to the capacity of these joints previously measured through static tests in phase one. The observation of common forms of damage in ceilings in earthquakes triggered the monotonic experiments carried out in the third phase of this research with the objective of investigating a simple and easily applicable mitigation strategy for existing or new suspended ceilings. The tests focused on the possibility of using proprietary cross-shaped clip elements ordinarily used to provide seismic gap as a strengthening solution for the weak components of a ceiling. The results showed that the solution was effective under both tension and compression loads through increasing load bearing capacity and ductility in grid connections. The feasibility of a novel type of suspended ceiling called fully-floating ceiling system was investigated through shaking table tests in the next phase of this study with the main goal of isolating the ceiling from the surrounding structure; thereby arresting the transfer of associated seismic forces from the structure to the ceiling. The fully-floating ceiling specimen was freely hung from the floor above lacking any lateral bracing and connections with the perimeter. Throughout different tests, a satisfactory agreement between the fully-floating ceiling response and simple pendulum theory was demonstrated. The addition of isolation material in perimeter gaps was found effective in inducing extra damping and protecting the ceiling from pounding impact; resulting in much reduced ceiling displacements and accelerations. The only form of damage observed throughout the random floor motion tests and the sinusoidal tests was a panel dislodgement observed in a test due to successive poundings between the ceiling specimen and the surrounding beams at resonant frequencies. Partition walls as the first effective NSE in direct interaction with ceilings were the topic of the final experimental phase. Low-damage drywall partitions proposed in a previous study in the UC were tested with two common forms of suspended ceiling: braced and perimeter-fixed. The experiments investigated the in-plane and out-of-plane performance of the low-damage drywall partitions, as well as displacement compatibility between these walls and the suspended ceilings. In the braced ceiling experiment, where no connection was made between ceiling grids and surrounding walls no damage in the grid system or partitions was observed. However, at high drift values panel dislodgement was observed on corners of the ceiling where the free ends of grids were not restrained against spreading. This could be prevented by framing the grid ends using a perimeter angle that is riveted only to the grid members while keeping sufficient clearance from the perimeter walls. In the next set of tests with the perimeter-fixed ceiling, no damage was observed in the ceiling system or the drywalls. Based on the results of the experiments it was concluded that the tested ceiling had enough flexibility to accommodate the relative displacement between two perpendicular walls up to the inter-storey drifts achieved. The experiments on perimeter-fixed ceilings were followed by numerical simulations of the performance of these ceilings in a finite element model developed in the structural analysis software, SAP2000. This model was relatively simple and easy to develop and was able to replicate the experimental results to a reasonable degree. Filtering was applied to the experimental output to exclude the effect of high frequency noise and tile-grid impact. The developed model generally simulated the acceleration responses well but underestimated the peak ceiling grid accelerations. This was possibly because the peak values in time histories were affected by impact occurring at very short periods. The model overestimated the axial forces in ceiling grids which was assumed to be caused by the initial assumptions made about the tributary area or constant acceleration associated with each grid line in the direction of excitation. Otherwise, the overall success of the numerical modelling in replicating the experimental results implies that numerical modelling using conventional structural analysis software could be used in engineering practice to analyse alternative ceiling geometries proposed for application to varying structural systems. This however, needs to be confirmed through similar analyses on other ceiling examples from existing instrumented buildings during real earthquakes. As the concluding part of this research the final phase addressed the issues raised following the review of existing ceiling standards and guidelines. The applicability of the research findings to current practice and their implications were discussed. Finally, an example was provided for the design of a suspended ceiling utilising the new knowledge acquired in this research.
