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Research papers, The University of Auckland Library

The current seismic design practice for reinforced concrete (RC) walls has been drawn into question following the Canterbury earthquakes. An overview of current research being undertaken at the University of Auckland into the seismic behaviour of RC walls is presented. The main objectives of this research project are to understand the observed performance of several walls in Christchurch, quantify the seismic loads on RC walls, and developed improved design procedures for RC walls that will assist in revisions to NZS 3101. A database summarising of the performance of RC wall buildings in the Christchurch CBD was collated to identify damage modes and case-study buildings. A detailed investigation is underway to verify the seismic performance of lightly reinforced concrete walls and an experimental setup has been developed to subject RC wall specimen to loading that is representative of a multi-storey building. Numerical modelling is being used to understand the observed performance of several case-study RC walls buildings in Christchurch. Of particular interest is the influence that interactions between walls and other structural elements have on the seismic response of buildings and the loads generated on RC walls.

Research papers, The University of Auckland Library

The city of Christchurch has experienced over 10,000 aftershocks since the 4th of September 2010 earthquake of which approximately 50 have been greater than magnitude 5. The damage caused to URM buildings in Christchurch over this sequence of earthquakes has been well documented. Due to the similarity in age and construction of URM buildings in Adelaide, South Australia and Christchurch (they are sister cities, of similar age and heritage), an investigation was conducted to learn lessons for Adelaide based on the Christchurch experience. To this end, the number of URM buildings in the central business districts of both cities, the extent of seismic strengthening that exists in both cities, and the relative earthquake hazards for both cities were considered. This paper will report on these findings and recommend strategies that the city of Adelaide could consider to significantly reduce the seismic risk posed by URM buildings in future earthquake.

Research papers, The University of Auckland Library

Territorial authorities in New Zealand are responding to regulatory and market forces in the wake of the 2011 Christchurch earthquake to assess and retrofit buildings determined to be particularly vulnerable to earthquakes. Pending legislation may shorten the permissible timeframes on such seismic improvement programmes, but Auckland Council’s Property Department is already engaging in a proactive effort to assess its portfolio of approximately 3500 buildings, prioritise these assets for retrofit, and forecast construction costs for improvements. Within the programme structure, the following varied and often competing factors must be accommodated: * The council’s legal, fiscal, and ethical obligations to the people of Auckland per building regulations, health and safety protocols, and economic growth and urban development planning strategies; * The council’s functional priorities for service delivery; * Varied and numerous stakeholders across the largest territorial region in New Zealand in both population and landmass; * Heritage preservation and community and cultural values; and * Auckland’s prominent economic role in New Zealand’s economy which requires Auckland’s continued economic production post-disaster. Identifying those buildings most at risk to an earthquake in such a large and varied portfolio has warranted a rapid field assessment programme supplemented by strategically chosen detailed assessments. Furthermore, Auckland Council will benefit greatly in time and resources by choosing retrofit solutions, techniques, and technologies applicable to a large number of buildings with similar configurations and materials. From a research perspective, the number and variety of buildings within the council’s property portfolio will provide valuable data for risk modellers on building typologies in Auckland, which are expected to be fairly representative of the New Zealand building stock as a whole.

Research papers, The University of Auckland Library

The paper proposes a simple method for quick post-earthquake assessment of damage and condition of a stock of bridges in a transportation network using seismic data recorded by a strong motion array. The first part of the paper is concerned with using existing free field strong motion recorders to predict peak ground acceleration (PGA) at an arbitrary bridge site. Two methods are developed using artificial neural networks (a single network and a committee of neural networks) considering influential parameters, such as seismic magnitude, hypocentral depth and epicentral distance. The efficiency of the proposed method is explored using actual strong motion records from the devastating 2010 Darfield and 2011 Christchurch earthquakes in New Zealand. In the second part, two simple ideas are outlined how to infer the likely damage to a bridge using either the predicted PGA and seismic design spectrum, or a broader set of seismic metrics, structural parameters and damage indices.

Research papers, The University of Auckland Library

Having a quick but reliable insight into the likelihood of damage to bridges immediately after an earthquake is an important concern especially in the earthquake prone countries such as New Zealand for ensuring emergency transportation network operations. A set of primary indicators necessary to perform damage likelihood assessment are ground motion parameters such as peak ground acceleration (PGA) at each bridge site. Organizations, such as GNS in New Zealand, record these parameters using distributed arrays of sensors. The challenge is that those sensors are not installed at, or close to, bridge sites and so bridge site specific data are not readily available. This study proposes a method to predict ground motion parameters for each bridge site based on remote seismic array recordings. Because of the existing abundant source of data related to two recent strong earthquakes that occurred in 2010 and 2011 and their aftershocks, the city of Christchurch is considered to develop and examine the method. Artificial neural networks have been considered for this research. Accelerations recorded by the GeoNet seismic array were considered to develop a functional relationship enabling the prediction of PGAs. http://www.nzsee.org.nz/db/2013/Posters.htm

Research papers, The University of Auckland Library

Quick and reliable assessment of the condition of bridges in a transportation network after an earthquake can greatly assist immediate post-disaster response and long-term recovery. However, experience shows that available resources, such as qualified inspectors and engineers, will typically be stretched for such tasks. Structural health monitoring (SHM) systems can therefore make a real difference in this context. SHM, however, needs to be deployed in a strategic manner and integrated into the overall disaster response plans and actions to maximize its benefits. This study presents, in its first part, a framework of how this can be achieved. Since it will not be feasible, or indeed necessary, to use SHM on every bridge, it is necessary to prioritize bridges within individual networks for SHM deployment. A methodology for such prioritization based on structural and geotechnical seismic risks affecting bridges and their importance within a network is proposed in the second part. An example using the methodology application to selected bridges in the medium-sized transportation network of Wellington, New Zealand is provided. The third part of the paper is concerned with using monitoring data for quick assessment of bridge condition and damage after an earthquake. Depending on the bridge risk profile, it is envisaged that data will be obtained from either local or national seismic monitoring arrays or SHM systems installed on bridges. A method using artificial neural networks is proposed for using data from a seismic array to infer key ground motion parameters at an arbitrary bridges site. The methodology is applied to seismic data collected in Christchurch, New Zealand. Finally, how such ground motion parameters can be used in bridge damage and condition assessment is outlined. AM - Accepted manuscript

Research papers, The University of Auckland Library

Seismic retrofitting of unreinforced masonry buildings using posttensioning has been the topic of many recent experimental research projects. However, the performance of such retrofit designs in actual design level earthquakes has previously been poorly documented. In 1984 two stone masonry buildings within The Arts Centre of Christchurch received posttensioned seismic retrofits, which were subsequently subjected to design level seismic loads during the 2010/2011 Canterbury earthquake sequence. These 26 year old retrofits were part of a global scheme to strengthen and secure the historic building complex and were subject to considerable budgetary constraints. Given the limited resources available at the time of construction and the current degraded state of the steel posttension tendons, the posttensioned retrofits performed well in preventing major damage to the overall structure of the two buildings in the Canterbury earthquakes. When compared to other similar unretrofitted structures within The Arts Centre, it is demonstrated that the posttensioning significantly improved the in-plane and out-of-plane wall strength and the ability to limit residual wall displacements. The history of The Arts Centre buildings and the details of the Canterbury earthquakes is discussed, followed by examination of the performance of the posttension retrofits and the suitability of this technique for future retrofitting of other historic unreinforced masonry buildings. http://www.aees.org.au/downloads/conference-papers/2013-2/

Research papers, The University of Auckland Library

The Canterbury earthquake series of 2010/2011 has turned the city of Christchurch into a full scale natural laboratory testing the structural and non-structural response of buildings under moderate to very severe earthquake shaking. The lessons learned from this, which have come at great cost socially and economically, are extremely valuable in increasing our understanding of whole building performance in severe earthquakes. Given current initiatives underway on both sides of the Tasman towards developing joint Australasian steel and composite steel/concrete design and construction standards that would span a very wide range of geological conditions and seismic zones, these lessons are relevant to both countries. This paper focusses on the performance of steel framed buildings in Christchurch city, with greatest emphasis on multi-storey buildings, but also covering single storey steel framed buildings and light steel framed housing. It addresses such issues as the magnitude and structural impact of the earthquake series, importance of good detailing, lack of observed column base hinging, the excellent performance of composite floors and it will briefly cover research underway to quantify some of these effects for use in design.

Research papers, The University of Auckland Library

It is well known that buildings constructed using unreinforced masonry (URM) are susceptible to damage from earthquake induced lateral forces that may result in partial or full building collapse. The 2010/2011 Canterbury earthquakes are the most recent New Zealand example of destructive earthquakes, which have drawn people's attention to the inherent seismic weaknesses of URM buildings and anchored masonry veneer systems in New Zealand. A brief review of the data collected following the 2010 Darfield earthquake and more comprehensive documentation of data that was collected following the 2011 Christchurch earthquake is presented, along with the findings from subsequent data interrogation. Large stocks of earthquake prone vintage URM buildings that remain in New Zealand and in other seismically active parts of the world result in the need for minimally invasive and cost effective seismic retrofit techniques. The principal objective of the doctoral research reported herein was to investigate the applicability of near surface mounted (NSM) carbon fibre reinforced polymer (CFRP) strips as a seismic improvement technique. A comprehensive experimental program consisting of 53 pull tests is presented and is used to assess the accuracy of existing FRP-to-masonry bond models, with a modified model being proposed. The strength characteristics of vintage clay brick URM wall panels from two existing URM buildings was established and used as a benchmark when manufacturing replica clay brick test assemblages. The applicability of using NSM CFRP strips as a retrofitting technique for improving the shear strength and the ductility capacity of multi-leaf URM walls constructed using solid clay brick masonry is investigated by varying CFRP reinforcement ratios. Lastly, an experimental program was undertaken to validate the proposed design methodology for improving the strength capacity of URM walls. The program involved testing full-scale walls in a laboratory setting and testing full-scale walls in-situ in existing vintage URM buildings. Experimental test results illustrated that the NSM CFRP technique is an effective method to seismically strengthen URM buildings.

Research papers, The University of Auckland Library

Whole document is available to authenticated members of The University of Auckland until Feb. 2014. The increasing scale of losses from earthquake disasters has reinforced the need for property owners to become proactive in seismic risk reduction programs. However, despite advancement in seismic design methods and legislative frameworks, building owners are often reluctant to adopt mitigation measures required to reduce earthquake losses. The magnitude of building collapses from the recent Christchurch earthquakes in New Zealand shows that owners of earthquake prone buildings (EPBs) are not adopting appropriate risk mitigation measures in their buildings. Owners of EPBs are found unwilling or lack motivation to adopt adequate mitigation measures that will reduce their vulnerability to seismic risks. This research investigates how to increase the likelihood of building owners undertaking appropriate mitigation actions that will reduce their vulnerability to earthquake disaster. A sequential two-phase mixed methods approach was adopted for the research investigation. Multiple case studies approach was adopted in the first qualitative phase, followed by the second quantitative research phase that includes the development and testing of a framework. The research findings reveal four categories of critical obstacles to building owners‘ decision to adopt earthquake loss prevention measures. These obstacles include perception, sociological, economic and institutional impediments. Intrinsic and extrinsic interventions are proposed as incentives for overcoming these barriers. The intrinsic motivators include using information communication networks such as mass media, policy entrepreneurs and community engagement in risk mitigation. Extrinsic motivators comprise the use of four groups of incentives namely; financial, regulatory, technological and property market incentives. These intrinsic and extrinsic interventions are essential for enhancing property owners‘ decisions to voluntarily adopt appropriate earthquake mitigation measures. The study concludes by providing specific recommendations that earthquake risk mitigation managers, city councils and stakeholders involved in risk mitigation in New Zealand and other seismic risk vulnerable countries could consider in earthquake risk management. Local authorities could adopt the framework developed in this study to demonstrate a combination of incentives and motivators that yield best-valued outcomes. Consequently, actions can be more specific and outcomes more effective. The implementation of these recommendations could offer greater reasons for the stakeholders and public to invest in building New Zealand‘s built environment resilience to earthquake disasters.

Research papers, The University of Auckland Library

Unreinforced masonry (URM) is a construction type that was commonly adopted in New Zealand between the 1880s and 1930s. URM construction is evidently vulnerable to high magnitude earthquakes, with the most recent New Zealand example being the 22 February 2011 Mw6.3 Christchurch earthquake. This earthquake caused significant damage to a majority of URM buildings in the Canterbury area and resulted in 185 fatalities. Many URM buildings still exist in various parts of New Zealand today, and due to their likely poor seismic performance, earthquake assessment and retrofit of the remaining URM building stock is necessary as these buildings have significant architectural heritage and occupy a significant proportion of the nation’s building stock. A collaborative research programme between the University of Auckland and Reid Construction Systems was conducted to investigate an economical yet effective solution for retrofitting New Zealand’s existing URM building stock. This solution adopts the shotcrete technique using an Engineered Cementitious Composite (ECC), which is a polyvinyl alcohol fibre reinforced mortar that exhibits strain hardening characteristics. Collaborations have been formed with a number of consulting structural engineers throughout New Zealand to develop innovative and cost effective retrofit solutions for a number of buildings. Two such case studies are presented in this paper. http://www.concrete2013.com.au/technical-program/

Research papers, The University of Auckland Library

As a result of the 4 September 2010 Darfield earthquake and the more damaging 22 February 2011 Christchurch earthquake, considerable damage occurred to a significant number of buildings in Christchurch. The damage that occurred to the Christchurch Roman Catholic Cathedral of the Blessed Sacrament (commonly known as the Christchurch Basilica) as a result of the Canterbury earthquakes is reported, and the observed failure modes are identified. A previous strengthening intervention is outlined and the estimated capacity of the building is discussed. This strengthening was completed in 2004, and addressed the worst aspects of the building's seismic vulnerability. Urgent work was undertaken post-earthquake to secure parts of the building in order to limit damage and prevent collapse of unstable parts of the building. The approach taken for this securing is outlined, and the performance of the building and the previously installed earthquake strengthening intervention is evaluated.A key consideration throughout the project was the interaction between the structural securing requirements that were driven by the requirement to limit damage and mitigate hazards, and the heritage considerations. Lessons learnt from the strengthening that was carried out, the securing work undertaken, and the approach taken in making the building "safe" are discussed. Some conclusions are drawn with respect to the effectiveness of strengthening similar building types, and the approach taken to secure the building under active seismic conditions. AM - Accepted Manuscript

Research papers, University of Canterbury Library

Two projects are documented within this MEM Report: I. The first project examined what was learnt involving the critical infrastructure in the aftermath of natural disasters in the Canterbury region of New Zealand – the most prominent being the series of earthquakes between 2010 and 2011. The project identified several learning gaps, leading to recommendations for further investigations that could add significant value for the lifeline infrastructure community. II. Following the Lifeline Lesson Learnt Project, the Disaster Mitigation Guideline series was initiated with two booklets, one on Emergency Potable Water and a second on Emergency Sanitation. The key message from both projects is that we can and must learn from disasters. The projects described are part of the emergency management, and critical infrastructure learning cycles – presenting knowledge captured by others in a digestible format, enabling the lessons to be reapplied. Without these kinds of projects, there will be fewer opportunities to learn from other’s successes and failures when it comes to preparing for natural disasters.

Research papers, University of Canterbury Library

This study sought to investigate employee burnout within a post-disaster context by exploring teachers’ burnout perceptions and workplace attitudes in the aftermath of the 2010-2011 Christchurch earthquakes. The study hypothesised that burnout dimensions (emotional exhaustion and cynicism) would be related with the extent to which individuals and schools were impacted by the earthquakes, and with the quality of school support for staff and students (i.e., personal disaster impact, school disaster impact and school responsiveness to the disaster), with perceptions of role conflict and role overload, and with turnover intentions. Additionally, a Teacher Burnout Model was proposed whereby emotional exhaustion and cynicism were hypothesised to mediate the relationships between the independent variables (i.e., the disaster-related and role-related variables) and turnover intentions. 125 primary, intermediate and secondary school teachers from the city of Christchurch completed an online survey. Results revealed that high role overload, high role conflict, high school disaster impact, and schools’ ineffective disaster coping responses, were associated with increased levels of emotional exhaustion and cynicism. Although greater impact of earthquakes on teachers’ personal lives was related to higher levels of emotional exhaustion, results revealed a non-significant relationship between personal disaster impact and cynicism. In the Teacher Burnout Model, the relationships between both role stress variables and turnover intentions were mediated by perceptions of emotional exhaustion. This study contributes novel findings to the burnout literature, and provides implications for schools and organisations operating within a disaster context.

Research papers, University of Canterbury Library

Disasters are rare events with major consequences; yet comparatively little is known about managing employee needs in disaster situations. Based on case studies of four organisations following the devastating earthquakes of 2010 - 2011 in Christchurch, New Zealand, this paper presents a framework using redefined notions of employee needs and expectations, and charting the ways in which these influence organisational recovery and performance. Analysis of in-depth interview data from 47 respondents in four organisations highlighted the evolving nature of employee needs and the crucial role of middle management leadership in mitigating the effects of disasters. The findings have counterintuitive implications for human resource functions in a disaster, suggesting that organisational justice forms a central framework for managing organisational responses to support and engage employees for promoting business recovery.

Research papers, University of Canterbury Library

During 2010 and 2011, major earthquakes caused widespread damage and the deaths of 185 people in the city of Christchurch. Damaged school buildings resulted in state intervention which required amendment of the Education Act of 1989, and the development of ‘site sharing agreements’ in undamaged schools to cater for the needs of students whose schools had closed. An effective plan was also developed for student assessment through establishing an earthquake impaired derived grade process. Previous research into traditional explanations of educational inequalities in the United Kingdom, the United States of America, and New Zealand were reviewed through various processes within three educational inputs: the student, the school and the state. Research into the impacts of urban natural disasters on education and education inequalities found literature on post disaster education systems but nothing could be found that included performance data. The impacts of the Canterbury earthquakes on educational inequalities and achievement were analysed over 2009-2012. The baseline year was 2009, the year before the first earthquake, while 2012 is seen as the recovery year as no schools closed due to seismic events and there was no state intervention into the education of the region. National Certificate of Educational Achievement (NCEA) results levels 1-3 from thirty-four secondary schools in the greater Christchurch region were graphed and analysed. Regression analysis indicates; in 2009, educational inequalities existed with a strong positive relationship between a school’s decile rating and NCEA achievement. When schools were grouped into decile rankings (1-10) and their 2010 NCEA levels 1-3 results were compared with the previous year, the percentage of change indicates an overall lower NCEA achievement in 2010 across all deciles, but particularly in lower decile schools. By contrast, when 2011 NCEA results were compared with those of 2009, as a percentage of change, lower decile schools fared better. Non site sharing schools also achieved higher results than site sharing schools. State interventions, had however contributed towards student’s achieving national examinations and entry to university in 2011. When NCEA results for 2012 were compared to 2009 educational inequalities still exist, however in 2012 the positive relationship between decile rating and achievement is marginally weaker than in 2009. Human ethics approval was required to survey one Christchurch secondary school community of students (aged between 12 and 18), teachers and staff, parents and caregivers during October 2011. Participation was voluntary and without incentives, 154 completed questionnaires were received. The Canterbury earthquakes and aftershocks changed the lives of the research participants. This school community was displaced to another school due to the Christchurch earthquake on 22 February 2011. Research results are grouped under four geographical perspectives; spatial impacts, socio-economic impacts, displacement, and health and wellbeing. Further research possibilities include researching the lag effects from the Canterbury earthquakes on school age children.

Research papers, University of Canterbury Library

The aim of this thesis was to examine the spatial and the temporal patterns of anxiety and chest pain resulting from the Canterbury, New Zealand earthquaeks. Three research objectives were identified: examine any spatial or termporal clusters of anxiety and chest pain; examine the associations between anxiety, chest pain and damage to neighbourhood; and determine any statistically significant difference in counts of anxiety and chest pain after each earthquake or aftershock which resulted in severe damage. Measures of the extent of liquefaction the location of CERA red-zones were used as proxy measures for earthquake damage. Cases of those who presented to Christchurch Public Hospital Emergency Department with either anxiety or chest pain between May 2010 and April 2012 were aggregated to census area unit (CAU) level for analysis. This thesis has taken a unique approach to examining the spatial and spatio-temporal variations of anxiety and chest pain after an earthquake and offers unique results. This is the first study of its kind to use a GIS approach when examining Canterbury specific earthquake damage and health variables at a CAU level after the earthquakes. Through the use of spatio-termporal scan modelling, negative and linear regression modelling and temporal linear modelling with dummy variables this research was able to conclude there are significant spatial and temporal variations in anxiety and chest pain resulting from the earthquakes. The spatio-termporal scan modelling identified a hot cluster of both anxiety and chest pain within Christchurch at the same time the earthquakes occurred. The negative binomial model found liquefaction to be a stronger predictor of anxiety than the Canterbury Earthquake Recovery Authority's (CERA) land zones. The linear regression model foun chest pain to be positively associated with all measures of earthquake damage with the exception of being in the red-zone. The temporal modelling identified a significant increase in anxiety cases one month after a major earthquake, and chest pain cases spiked two weeks after an earthquake and gradually decreased over the following five weeks. This research was limited by lack of control period data, limited measures of earthquake damage, ethical restrictions, and the need for population tracking data. The findings of this research will be useful in the planning and allocation of mental wellbeing resources should another similar event like the Canterbury Earthquakes occur in New Zealand.

Research papers, University of Canterbury Library

Fatal earthquakes such as that which occurred in Christchurch on February 22nd 2011, can result in survivors having difficulties with cognitively processing the event, which may be the precursor to posttraumatic stress symptoms. Trauma related dissociation has been proposed to be a mechanism related to these cognitive processing difficulties. Most research focusing on information processing and dissociation post-trauma has conducted controlled analogue studies or has not focused solely on information processing and dissociation. There is also scant research on these constructs across therapy. In response to this gap in research, two studies were developed. An association was proposed between dissociation and information processing as demonstrated by an increase in conceptual processing and a reduction in dissociation. It was predicted that an improvement in these constructs would be related to a reduction in PTSD symptoms over therapy. Study1 applied a case-study design to 5 individuals who were attending therapy for post-traumatic stress disorder in response to the trauma they had experienced from the Christchurch earthquakes. Study 2 assessed information processing and dissociation (via self and observer report) in 20 individuals who had direct exposure to the effects of the earthquake. Earthquake information processing and dissociation were assessed as they were happening nearly two year’s post-quake using correlation analyses and hierarchical regressions. The hypotheses were partially confirmed, in that an increase in conceptual processing was not shown to be associated with a reduction in dissociation. However, an increase in conceptual processing was shown to be related to trauma symptom improvement particularly for re-experiencing symptoms. In addition, study 2 demonstrated a possible relationship between trait dissociation and arousal symptoms. These findings partially support the proposed role information processing and dissociation play in the recovery from PTSD. The findings suggest that trauma related difficulties should be assessed as early as possible to resolve issues related to a delay in symptom reporting.

Research papers, University of Canterbury Library

Christchurch earthquake events have raised questions on the adequacy of performance-based provisions in the current national building code. At present, in the building code the performance objectives are expressed in terms of safety and health criteria that could affect building occupants. In general, under the high intensity Christchurch events, buildings performed well in terms of life-safety (with a few exceptions) and it proved that the design practices adopted for those buildings could meet the performance objectives set by the building code. However, the damage incurred in those buildings resulted in unacceptably high economic loss. It is timely and necessary to revisit the objectives towards building performance in the building code and to include provisions for reducing economic implications in addition to the current requirements. Based on the observed performance of some buildings, a few specific issues in the current design practices that could have contributed to extensive damage have been identified and recommended for further research leading towards improved performance of structures. In particular, efforts towards innovative design/construction solutions with low-damage concepts are encouraged. New Zealand has been one of the leading countries in developing many innovative technologies. However, such technically advanced research findings usually face challenges towards implementation. Some of the reasons include: (i) lack of policy requirements; (iii) absence of demonstrated performance of new innovations to convince stakeholders; and (iv) non-existence of design guidelines. Such barriers significantly affect implementation of low damage construction and possible strategies to overcome those issues are discussed in this paper.

Research papers, University of Canterbury Library

This paper presents a critical evaluation of vertical ground motions observed in the Canterbury earthquake sequence. The abundance of strong near-source ground-motion recordings provides an opportunity to comprehensively review the estimation of vertical ground motions via the New Zealand Standard for earthquake loading, NZS1170.5:2004, and empirical ground motion prediction equations (GMPEs). An in-depth review of current GMPEs is carried out to determine the existing trends and characteristics present in the empirical models. Results illustrate that vertical ground motion amplitudes estimated based on NZS1170.5:2004 are significantly unconservative at short periods and near-source distances. While conventional GMPEs provide an improved prediction, in many instances they too underpredict vertical ground motion accelerations at short periods and near-source distances.

Research papers, University of Canterbury Library

In this paper, the characteristics of near-fault ground motions recorded during the Mw7.1 Darfield and Mw 6.2 Christchurch earthquakes are examined and compared with existing empirical models. The characteristics of forward-directivity effects are first examined using a wavelet-based pulse-classification algorithm. This is followed by an assessment of the adequacy of empirical models which aim to capture the effect of directivity effects on amplifying the acceleration response spectra; and the period and peak velocity of the forward-directivity pulse. It is illustrated that broadband directivity models developed by Somerville et al. (1997) and Abrahamson (2000) generally under-predict the observed amplification of response spectral ordinates at longer vibration periods. In contrast, a recently developed narrowband model by Shahi and Baker (2011) provides significantly improved predictions by amplifying the response spectra within a small range of periods surrounding the directivity pulse period. Although the empirical predictions of the pulse period are generally favourable for the Christchurch earthquake, the observations from the Darfield earthquake are significantly under-predicted. The elongation in observed pulse periods is inferred as being a result of the soft sedimentary soils of the Canterbury basin. However, empirical predictions of the observed peak velocity associated with the directivity pulse are generally adequate for both events.

Research papers, University of Canterbury Library

Damage to ceiling systems resulted in a substantial financial loss to building owners in the Canterbury earthquakes. In some buildings, collapse of ceilings could easily have resulted in severe injury to occupants. This paper summarizes the types of ceiling damage observed in the Canterbury earthquakes, and draws useful lessons from the observed performance of different types of ceiling systems. Existing ceiling manufacturing and installing practices/regulations in New Zealand are critically scrutinized to identify deficiencies, and measures are suggested to improve the practice so that the damage to ceilings and the resulting loss are minimized in future earthquakes.

Research papers, University of Canterbury Library

The capability of self-compacting concrete (SCC) in flowing through and filling in even the most congested areas makes it ideal for being used in congested reinforced concrete (RC) structural members such as beam-column joints (BCJ). However, members of tall multi-storey structures impose high capacity requirements where implementing normal-strength self-compacting concrete is not preferable. In the present study, a commercially reproducible high-strength self-compacting concrete (HSSCC), a conventionally vibrated high-strength concrete (CVHSC) and a normal strength conventionally vibrated concrete (CVC) were designed using locally available materials in Christchurch, New Zealand. Following the guidelines of the New Zealand concrete standards NZS3101, seven beam-column joints (BCJ) were designed. Factors such as the concrete type, grade of reinforcement, amount of joint shear stirrups, axial load, and direction of casting were considered variables. All BCJs were tested under a displacement-controlled quasi-static reversed cyclic regime. The cracking pattern at different load levels and the mode of failure were also recorded. In addition, the load, displacement, drift, ductility, joint shear deformations, and elongation of the plastic hinge zone were also measured during the experiment. It was found that not only none of the seismically important features were compromised by using HSSCC, but also the quality of material and ease of construction boosted the performance of the BCJs.

Research papers, University of Canterbury Library

Novel Gel-push sampling was employed to obtain high quality samples of Christchurch sands from the Central Business District, at sites where liquefaction was observed in 22 February 2011, and 13 June 2011 earthquakes. The results of cyclic triaxial testing on selected undisturbed specimens of typical Christchurch sands are presented and compared to empirical procedures used by practitioners. This comparison suggests cyclic triaxial data may be conservative, and the Magnitude Scaling Factor used in empirical procedures may be unconservative for highly compressible soils during near source moderate to low magnitude events. Comparison to empirical triggering curves suggests the empirical method generally estimates the cyclic strength of Christchurch sands within a reasonable degree of accuracy as a screening evaluation tool for liquefaction hazard, however for sands with moderate to high fines content it may be significantly unconservative, highlighting the need for high quality sampling and testing on important projects where seismic performance is critical.

Research papers, University of Canterbury Library

The Canterbury region of New Zealand experienced four earthquakes greater than MW 6.0 between September 2010 and December 2011. This study employs system dynamics as well as hazard, recovery and organisational literature and brings together data collected via surveys, case studies and interviews with organisations affected by the earthquakes. This is to show how systemic interactions and interdependencies within and between industry and geographic sectors affect their recovery post-disaster. The industry sectors in the study are: construction for its role in the rebuild, information and communication technology which is a regional high-growth industry, trucking for logistics, critical infrastructure, fast moving consumer goods (e.g. supermarkets) and hospitality to track recovery through non-discretionary and discretionary spend respectively. Also in the study are three urban centres including the region’s largest Central Business District, which has been inaccessible since the earthquake of 22 February 2011 to the time of writing in February 2013. This work also highlights how earthquake effects propagated between sectors and how sectors collaborated to mitigate difficulties such as product demand instability. Other interacting factors are identified that influence the recovery trajectories of the different industry sectors. These are resource availability, insurance payments, aid from central government, and timely and quality recovery information. This work demonstrates that in recovering from disaster it is crucial for organisations to identify what interacting factors could affect their operations. Also of importance are efforts to reduce the organisation’s vulnerability and increase their resilience to future crises and in day-to-day operations. Lastly, the multi-disciplinary approach to understanding the recovery and resilience of organisations and industry sectors after disaster, leads to a better understanding of effects as well as more effective recovery policy.

Research papers, University of Canterbury Library

Fine grained sediment deposition in urban environments during natural hazard events can impact critical infrastructure and properties (urban terrain) leading to reduced social and economic function and potentially adverse public health effects. Therefore, clean-up of the sediments is required to minimise impacts and restore social and economic functionality as soon as possible. The strategies employed to manage and coordinate the clean-up significantly influence the speed, cost and quality of the clean-up operation. Additionally, the physical properties of the fine grained sediment affects the clean-up, transport, storage and future usage of the sediment. The goals of the research are to assess the resources, time and cost required for fine grained sediment clean-up in an urban environment following a disaster and to determine how the geotechnical properties of sediment will affect urban clean-up strategies. The thesis focuses on the impact of fine grained sediment (<1 mm) deposition from three liquefaction events during the Canterbury earthquake sequence (2010-2011) on residential suburbs and transport networks in Christchurch. It also presents how geotechnical properties of the material may affect clean-up strategies and methods by presenting geotechnical analysis of tephra material from the North Island of New Zealand. Finally, lessons for disaster response planning and decision making for clean-up of sediment in urban environments are presented. A series of semi-structured interviews of key stakeholders supported by relevant academic literature and media reports were used to record the clean-up operation coordination and management and to make a preliminary qualification of the Christchurch liquefaction ejecta clean-up (costs breakdown, time, volume, resources, coordination, planning and priorities). Further analysis of the costs and resources involved for better accuracy was required and so the analysis of Christchurch City Council road management database (RAMM) was done. In order to make a transition from general fine sediment clean-up to specific types of fine disaster sediment clean-up, adequate information about the material properties is required as they will define how the material will be handled, transported and stored. Laboratory analysis of young volcanic tephra from the New Zealand’s North Island was performed to identify their geotechnical properties (density, granulometry, plasticity, composition and angle of repose). The major findings of this research were that emergency planning and the use of the coordinated incident management system (CIMS) system during the emergency were important to facilitate rapid clean-up tasking, management of resources and ultimately recovery from widespread and voluminous liquefaction ejecta deposition in eastern Christchurch. A total estimated cost of approximately $NZ 40 million was calculated for the Christchurch City clean-up following the 2010-2011 Canterbury earthquake sequence with a partial cost of $NZ 12 million for the Southern part of the city, where up to 33% (418 km) of the road network was impacted by liquefaction ejecta and required clearing of the material following the 22 February 2011 earthquake. Over 500,000 tonnes of ejecta has been stockpiled at Burwood landfill for all three liquefaction inducing earthquake events. The average cost per kilometre for the event clean-up was $NZ 5,500/km (4 September 2010), $NZ 11,650/km (22 February 2011) and $NZ 11,185/km (13 June 2011). The duration of clean-up time of residential properties and the road network was approximately two to three months for each of the three liquefaction ejecta events; despite events volumes and spatial distribution of ejecta. Interviews and quantitative analysis of RAMM data revealed that the experience and knowledge gained from the Darfield earthquake (4 September 2010) clean-up increased the efficiency of the following Christchurch earthquake induced liquefaction ejecta clean-up events. Density, particle size, particle shape, clay content and moisture content, are the important geotechnical properties that need to be considered when planning for a clean-up method that incorporates collection, transport and disposal or storage. The geotechnical properties for the tephra samples were analysed to increase preparedness and reaction response of potentially affected North Island cities from possible product from the active volcanoes in their region. The geotechnical results from this study show that volcanic tephra could be used in road or construction material but the properties would have to be further investigated for a New Zealand context. Using fresh volcanic material in road, building or flood control construction requires good understanding of the material properties and precaution during design and construction to extra care, but if well planned, it can be economically beneficial.

Research papers, University of Canterbury Library

This thesis describes research into developing a client/server ar- chitecture for a mobile Augmented Reality (AR) application. Following the earthquakes that have rocked Christchurch the city is now changed forever. CityViewAR is an existing mobile AR application designed to show how the city used to look before the earthquakes. In CityViewAR 3D virtual building models are overlaid onto video captured by a smartphone camera. However the current version of CityViewAR only allows users to browse information stored on the mobile device. In this research the author extends the CityViewAR application to a client-server model so that anyone can upload models and annotations to a server and have this information viewable on any smartphone running the application. In this thesis we describe related work on AR browser architectures, the system we developed, a user evaluation of the prototype system and directions for future work.

Research papers, University of Canterbury Library

Coastal and river environments are exposed to a number of natural hazards that have the potential to negatively affect both human and natural environments. The purpose of this research is to explain that significant vulnerabilities to seismic hazards exist within coastal and river environments and that coasts and rivers, past and present, have played as significant a role as seismic, engineering or socio-economic factors in determining the impacts and recovery patterns of a city following a seismic hazard event. An interdisciplinary approach was used to investigate the vulnerability of coastal and river areas in the city of Christchurch, New Zealand, following the Canterbury Earthquake Sequence, which began on the 4th of September 2010. This information was used to identify the characteristics of coasts and rivers that make them more susceptible to earthquake induced hazards including liquefaction, lateral spreading, flooding, landslides and rock falls. The findings of this research are applicable to similar coastal and river environments elsewhere in the world where seismic hazards are also of significant concern. An interdisciplinary approach was used to document and analyse the coastal and river related effects of the Canterbury earthquake sequence on Christchurch city in order to derive transferable lessons that can be used to design less vulnerable urban communities and help to predict seismic vulnerabilities in other New Zealand and international urban coastal and river environments for the future. Methods used to document past and present features and earthquake impacts on coasts and rivers in Christchurch included using maps derived from Geographical Information Systems (GIS), photographs, analysis of interviews from coastal, river and engineering experts, and analysis of secondary data on seismicity, liquefaction potential, geology, and planning statutes. The Canterbury earthquake sequence had a significant effect on Christchurch, particularly around rivers and the coast. This was due to the susceptibility of rivers to lateral spreading and the susceptibility of the eastern Christchurch and estuarine environments to liquefaction. The collapse of river banks and the extensive cracking, tilting and subsidence that accompanied liquefaction, lateral spreading and rock falls caused damage to homes, roads, bridges and lifelines. This consequently blocked transportation routes, interrupted electricity and water lines, and damaged structures built in their path. This study found that there are a number of physical features of coastal and river environments from the past and the present that have induced vulnerabilities to earthquake hazards. The types of sediments found beneath eastern Christchurch are unconsolidated fine sands, silts, peats and gravels. Together with the high water tables located beneath the city, these deposits made the area particularly susceptible to liquefaction and liquefaction-induced lateral spreading, when an earthquake of sufficient size shook the ground. It was both past and present coastal and river processes that deposited the types of sediments that are easily liquefied during an earthquake. Eastern Christchurch was once a coastal and marine environment 6000 years ago when the shoreline reached about 6 km inland of its present day location, which deposited fine sand and silts over this area. The region was also exposed to large braided rivers and smaller spring fed rivers, both of which have laid down further fine sediments over the following thousands of years. A significant finding of this study is the recognition that the Canterbury earthquake sequence has exacerbated existing coastal and river hazards and that assessments and monitoring of these changes will be an important component of Christchurch’s future resilience to natural hazards. In addition, patterns of recovery following the Canterbury earthquakes are highlighted to show that coasts and rivers are again vulnerable to earthquakes through their ability to recovery. This city’s capacity to incorporate resilience into the recovery efforts is also highlighted in this study. Coastal and river areas have underlying physical characteristics that make them increasingly vulnerable to the effects of earthquake hazards, which have not typically been perceived as a ‘coastal’ or ‘river’ hazard. These findings enhance scientific and management understanding of the effects that earthquakes can have on coastal and river environments, an area of research that has had modest consideration to date. This understanding is important from a coastal and river hazard management perspective as concerns for increased human development around coastlines and river margins, with a high seismic risk, continue to grow.

Research papers, University of Canterbury Library

Ground motion observations from the most significant 10 events in the 2010-2011 Canterbury earthquake sequence at near-source sites are utilized to scrutinize New Zealand (NZ)-specific pseudo-spectral acceleration (SA) empirical ground motion prediction equations (GMPE) (Bradley 2010, Bradley 2013, McVerry et al. 2006). Region-specific modification factors based on relaxing the conventional ergodic assumption in GMPE development were developed for the Bradley (2010) model. Because of the observed biases with magnitude and source-to-site distance for the McVerry et al. (2006) model it is not possible to develop region-specific modification factors in a reliable manner. The theory of non-ergodic empirical ground motion prediction is then outlined, and applied to this 10 event dataset to determine systematic effects in the between- and within-event residuals which lead to modifications in the predicted median and standard deviation of the GMPE. By examining these systematic effects over sub-regions containing a total of 20 strong motion stations within the Canterbury area, modification factors for use in region-specific ground motion prediction are proposed. These modification factors, in particular, are suggested for use with the Bradley et al. (2010) model in Canterbury-specific probabilistic seismic hazard analysis (PSHA) to develop revised design response, particularly for long vibration periods.