On November 14, 2016 an earthquake struck the rural districts of Kaikōura and Hurunui on New Zealand’s South Island. The region—characterized by small dispersed communities, a local economy based on tourism and agriculture, and limited transportation connections—was severely impacted. Following the quake, road and rail networks essential to maintaining steady flows of goods, visitors, and services were extensively damaged, leaving agrifood producers with significant logistical challenges, resulting in reduced productivity and problematic market access. Regional tourism destinations also suffered with changes to the number, characteristics, and travel patterns of visitors. As the region recovers, there is renewed interest in the development and promotion of agrifood tourism and trails as a pathway for enhancing rural resilience, and a growing awareness of the importance of local networks. Drawing on empirical evidence and insights from a range of affected stakeholders, including food producers, tourism operators, and local government, we explore the significance of emerging agrifood tourism initiatives for fostering diversity, enhancing connectivity, and building resilience in the context of rural recovery. We highlight the motivation to diversify distribution channels for agrifood producers, and strengthen the region’s tourism place identity. Enhancing product offerings and establishing better links between different destinations within the region are seen as essential. While such trends are common in rural regions globally, we suggest that stakeholders’ shared experience with the earthquake and its aftermath has opened up new opportunities for regeneration and reimagination, and has influenced current agrifood tourism trajectories. In particular, additional funding for tourism recovery marketing and product development after the earthquake, and an emphasis on greater connectivity between the residents and communities through strengthening rural networks and building social capital within and between regions, is enabling more resilient and sustainable futures.
There is growing expectation that local volunteers will play a more integrated role in disaster response, yet emergent groups are often ‘outsiders’ to crisis management, prompting questions of the conditions and processes by which these groups can forge relationships with established response agencies, and the tensions which can arise those interactions. This article analyses how student-led volunteers, as an emergent group, nevertheless gained “authority to operate” in the aftermath of the 2010-2011 earthquakes in Canterbury, New Zealand. Our study demonstrates how established response agencies and emergent groups can form hugely impactful and mutually supportive relationships. However, our analysis also points to two interrelated tensions that can arise, regarding the terms by which emergent groups are recognised, and the ‘distance’ considered necessary between emergent groups and established response agencies. The discussion considers implications for inclusiveness, risk and responsibility if emergent volunteers are to be further integrated into disaster response.
The Manchester Courts building was a heritage building located in central Christchurch (New Zealand) that was damaged in the Mw 7.1 Darfield earthquake on 4 September 2010 and subsequently demolished as a risk reduction exercise. Because the building was heritage listed, the decision to demolish the building resulted in strong objections from heritage supporters who were of the opinion that the building had sufficient residual strength to survive possible aftershock earthquakes. On 22 February 2011 Christchurch was struck by a severe aftershock, leading to the question of whether building demolition had proven to be the correct risk reduction strategy. Finite element analysis was used to undertake a performance-based assessment, validating the accuracy of the model using the damage observed in the building before its collapse. In addition, soil-structure interaction was introduced into the research due to the comparatively low shear wave velocity of the soil. The demolition of a landmark heritage building was a tragedy that Christchurch will never recover from, but the decision was made considering safety, societal, economic and psychological aspects in order to protect the city and its citizens. The analytical results suggest that the Manchester Courts building would have collapsed during the 2011 Christchurch earthquake, and that the collapse of the building would have resulted in significant fatalities.
While societal messages can encourage an unhealthy strive for perfection, the notion of embracing individual flaws and openly displaying vulnerabilities can appear foreign and outlandish. However, when fallibility is acknowledged and imperfection embraced, intimate relationships built on foundations of acceptance, trust and understanding can be established. In an architectural context, similar deep-rooted connections can be formed between a people and a place through the retention of layers of historical identity. When a building is allowed to age with blemishes laid bare for all to see, an architectural work can exhibit a sense of 'humanising vulnerability' where the bruises and scars it bears are able to visually communicate its contextual narrative. This thesis explores the notion of designing to capitalise on past decay through revitalisation of the former Wood Brothers Flour Mill in Addington, Christchurch (1891). Known as one of the city's last great industrial buildings, the 130-year-old structure remains hugely impressive due to its sheer size and scale despite being abandoned and subject to vandalism for a number of years. Its condition of obsolescence ensured the retention of visible signs of wear and tear in addition to the extensive damage caused by the 2010-12 Canterbury earthquakes. In offering a challenge to renovation and reconstruction as a means of conservation, this thesis asks if 'doing less' has the potential to 'do more'. How can an understanding of architecture as an ongoing process inform a design approach to celebrate ageing and patina? While the complex is undergoing redevelopment at the time of writing, the design project embraces the condition of the historic buildings in the immediate aftermath of the earthquakes and builds upon the patina of the mill and adjacent flour and grain store in developing a design for their adaptation as a micro-distillery. Research into the traditional Japanese ideology of wabi-sabi and its practical applications form the basis for a regenerative design approach which finds value in imperfection, impermanence and incompleteness. The thesis combines a literature review, precedent review and site analysis together with a design proposal. This thesis shows that adaptive reuse projects can benefit from an active collaboration with the processes of decay. Instead of a mindset where an architectural work is considered the finished article upon completion of construction, an empathetic and sensitive design philosophy is employed in which careful thought is given to the continued preservation and evolution of a structure with the recognition that evidence of past wear, tear, patina and weathering can all contribute positively to a building's future. In this fashion, rather than simply remaining as relics of the past, buildings can allow the landscape of their urban context to shape and mould them to ensure that their architectural experience can continue to be enjoyed by generations to come.
Little is known about The Wizard of New Zealand who took centre stage in Christchurch's Cathedral Square from the 70s until the Christchurch earthquakes in 2011, which saw the city in a state of disrepair. A man who challenged political, social and cultural ideology, The Wizard posed provocative questions in this public space, much to the delight, and sometimes dismay, of passersby. But the background to why The Wizard was there in the first place has been something of a mystery... until now. Sonia Yee finds out more in this episode of Eyewitness.
“William Wilson was formerly a cabbage dealer in Canterbury; but fourteen years ago he was poor, whereas now he is rich, a circumstance attributable to a lucky speculation in a piece of land …
Cobb & Co, Corner of Cashel and High Streets c. 1880. Source: Christchurch City Libraries Photo Collection 22, Img 00803, Private Collection For as far back as 1856, when the first hansom cab p…
John Jauncey Buchanan and his Valuable Allotment Before arrival in Christchurch, the family of Scotsman John Jauncey Buchanan purchased land on what would become the centre of Christchurch. It was …
Construction and Demolition (C&D) waste contributes to over 50% of New Zealand’s overall waste. Materials such as timber, plasterboard, and concrete make up 81% of the C&D waste that goes into landfills each year. Alongside this, more than 235 heritage-listed buildings have been demolished in Christchurch since the 2011 earthquakes. This research portfolio aims to find a solution to decrease C&D waste produced by demolishing heritage buildings. With the recent announcement of The Cathedral of the Blessed Sacrament’s demolition, this will be another building added to the list of lost heritage in Christchurch. This research portfolio aims to bridge the relationship between heritage and waste through the recycling and reuse of the demolished materials, exploring the idea that history and heritage are preserved through building material reuse. This research portfolio mainly focuses on reducing construction and demolition waste in New Zealand, using the design of a new Catholic Cathedral as a vessel. This thesis will challenge how the construction and design industry deals with the demolition of heritage buildings and their contribution to New Zealand’s waste. It aims to explore the idea of building material reuse not only to reduce waste but also to retain the history and heritage of the demolished building within the materials.
Ōtautahi-Christchurch faces the future in an enviable position. Compared to other New Zealand cities Christchurch has lower housing costs, less congestion, and a brand-new central city emerging from the rubble of the 2011 earthquakes. ‘Room to Breathe: designing a framework for medium density housing (MDH) in Ōtautahi-Christchurch’ seeks to answer the timely question how can medium density housing assist Ōtautahi-Christchurch to respond to growth in a way that supports a well-functioning urban environment? Using research by design, the argument is made that MDH can be used to support a safe, accessible, and connected urban environment that fosters community, while retaining a level of privacy. This is achieved through designing a neighbourhood concept addressing 3 morphological scales- macro- the city; meso- the neighbourhood; and micro- the home and street. The scales are used to inform a design framework for MDH specific to Ōtautahi-Christchurch, presenting a typological concept that takes full advantage of the benefits higher density living has to offer. Room to Breathe proposes repurposing underutilised areas surrounding existing mass transit infrastructure to provide a concentrated populous who do not solely rely on private vehicles for transport. By considering all morphological scales Room to Breathe provides one suggestion on how MDH could become accepted as part of a well-functioning urban environment.
PurposeThe purpose of this research is to highlight the role of not-for-profit (NFP) organisations in enhancing disaster preparedness. The authors set out to understand their perspectives and practices in regard to disaster preparedness activities to support people who live precarious lives, especially those who live as single parents who are the least prepared for disasters.Design/methodology/approachThe research draws on in-depth, semi-structured interviews with 12 staff members, either in a group setting or individually, from seven NFP organisations, who were located in Ōtautahi (Christchurch) and Kaiapoi in Aotearoa New Zealand. These participants were interviewed eight years after the 2011 Christchurch earthquake.FindingsFour key narrative tropes or elements were drawn from across the interviews and were used to structure the research results. These included: “essential” support services for people living precarious lives; assisting people to be prepared; potential to support preparedness with the right materials and relationships; resourcing to supply emergency goods.Originality/valueThis research contributes to disaster risk reduction practices by advocating for ongoing resourcing of NFP groups due to their ability to build a sense of community and trust while working with precarious communities, such as single parents.
Advanced seismic effective-stress analysis is used to scrutinize the liquefaction performance of 55 well-documented case-history sites from Christchurch. The performance of these sites during the 2010-2011 Canterbury earthquake sequence varied significantly, from no liquefaction manifestation at the ground surface (in any of the major events) to severe liquefaction manifestation in multiple events. For the majority of the 55 sites, the simplified liquefaction evaluation procedures, which are conventionally used in engineering practice, could not explain these dramatic differences in the manifestation. Detailed geotechnical characterization and subsequent examination of the soil profile characteristics of the 55 sites identified some similarities but also important differences between sites that manifested liquefaction in the two major events of the sequence (YY-sites) and sites that did not manifest liquefaction in either event (NN-sites). In particular, while the YY-sites and NN-sites are shown to have practically identical critical layer characteristics, they have significant differences with regard to their deposit characteristics including the thickness and vertical continuity of their critical zones and liquefiable materials. A CPT-based effective stress analysis procedure is developed and implemented for the analyses of the 55 case history sites. Key features of this procedure are that, on the one hand, it can be fully automated in a programming environment and, on the other hand, it is directly equivalent (in the definition of cyclic resistance and required input data) to the CPT-based simplified liquefaction evaluation procedures. These features facilitate significantly the application of effective-stress analysis for simple 1D free-field soil-column problems and also provide a basis for rigorous comparisons of the outcomes of effective-stress analyses and simplified procedures. Input motions for the analyses are derived using selected (reference) recordings from the two major events of the 2010-2011 Canterbury earthquake sequence. A step-by-step procedure for the selection of representative reference motions for each site and their subsequent treatment (i.e. deconvolution and scaling) is presented. The focus of the proposed procedure is to address key aspects of spatial variability of ground motion in the near-source region of an earthquake including extended-source effects, path effects, and variation in the deeper regional geology.
In this thesis, focus is given to develop methodologies for rapidly estimating specific components of loss and downtime functions. The thesis proposes methodologies for deriving loss functions by (i) considering individual component performance; (ii) grouping them as per their performance characteristics; and (iii) applying them to similar building usage categories. The degree of variation in building stock and understanding their characteristics are important factors to be considered in the loss estimation methodology and the field surveys carried out to collect data add value to the study. To facilitate developing ‘downtime’ functions, this study investigates two key components of downtime: (i) time delay from post-event damage assessment of properties; and (ii) time delay in settling the insurance claims lodged. In these two areas, this research enables understanding of critical factors that influence certain aspects of downtime and suggests approaches to quantify those factors. By scrutinising the residential damage insurance claims data provided by the Earthquake Commission (EQC) for the 2010- 2011 Canterbury Earthquake Sequence (CES), this work provides insights into various processes of claims settlement, the time taken to complete them and the EQC loss contributions to building stock in Christchurch city and Canterbury region. The study has shown diligence in investigating the EQC insurance claim data obtained from the CES to get new insights and build confidence in the models developed and the results generated. The first stage of this research develops contribution functions (probabilistic relationships between the expected losses for a wide range of building components and the building’s maximum response) for common types of claddings used in New Zealand buildings combining the probabilistic density functions (developed using the quantity of claddings measured from Christchurch buildings), fragility functions (obtained from the published literature) and cost functions (developed based on inputs from builders) through Monte Carlo simulations. From the developed contribution functions, glazing, masonry veneer, monolithic and precast concrete cladding systems are found to incur 50% loss at inter-storey drift levels equal to 0.027, 0.003, 0.005 and 0.011, respectively. Further, the maximum expected cladding loss for glazing, masonry veneer, monolithic, precast concrete cladding systems are found to be 368.2, 331.9, 365.0, and 136.2 NZD per square meter of floor area, respectively. In the second stage of this research, a detailed cost breakdown of typical buildings designed and built for different purposes is conducted. The contributions of structural and non- structural components to the total building cost are compared for buildings of different usages, and based on the similar ratios of non-structural performance group costs to the structural performance group cost, four-building groups are identified; (i) Structural components dominant group: outdoor sports, stadiums, parkings and long-span warehouses, (ii) non- structural drift-sensitive components dominant group: houses, single-storey suburban buildings (all usages), theatres/halls, workshops and clubhouses, (iii) non-structural acceleration- sensitive components dominant group: hospitals, research labs, museums and retail/cold stores, and (iv) apartments, hotels, offices, industrials, indoor sports, classrooms, devotionals and aquariums. By statistically analysing the cost breakdowns, performance group weighting factors are proposed for structural, and acceleration-sensitive and drift-sensitive non-structural components for all four building groups. Thus proposed building usage groupings and corresponding weighting factors facilitate rapid seismic loss estimation of any type of building given the EDPs at storey levels are known. A model for the quantification of post-earthquake inspection duration is developed in the third stage of this research. Herein, phase durations for the three assessment phases (one rapid impact and two rapid building) are computed using the number of buildings needing inspections, the number of engineers involved in inspections and a phase duration coefficient (which considers the median building inspection time, efficiency of engineer and the number of engineers involved in each assessment teams). The proposed model can be used: (i) by national/regional authorities to decide the length of the emergency period following a major earthquake, and estimate the number of engineers required to conduct a post-earthquake inspection within the desired emergency period, and (ii) to quantify the delay due to inspection for the downtime modelling framework. The final stage of this research investigates the repair costs and insurance claim settlement time for damaged residential buildings in the 2010-2011 Canterbury earthquake sequence. Based on the EQC claim settlement process, claims are categorized into three groups; (i) Small Claims: claims less than NZD15,000 which were settled through cash payment, (ii) Medium Claims: claims less than NZD100,000 which were managed through Canterbury Home Repair Programme (CHRP), and (iii) Large Claims: claims above NZD100,000 which were managed by an insurance provider. The regional loss ratio (RLR) for greater Christchurch for three events inducing shakings of approximate seismic intensities 6, 7, and 8 are found to be 0.013, 0.066, and 0.171, respectively. Furthermore, the claim duration (time between an event and the claim lodgement date), assessment duration (time between the claim lodgement day and the most recent assessment day), and repair duration (time between the most recent assessment day and the repair completion day) for the insured residential buildings in the region affected by the Canterbury earthquake sequence is found to be in the range of 0.5-4 weeks, 1.5- 5 months, and 1-3 years, respectively. The results of this phase will provide useful information to earthquake engineering researchers working on seismic risk/loss and insurance modelling.
While it is well known that challenging and distressing events can negatively impact people’s psychological and physical state, increasingly researchers have investigated how challenging or stressful life circumstances can lead to the phenomenon of posttraumatic growth: positive psychological or life changes that can emerge from potentially traumatic events. Posttraumatic growth has been investigated primarily with people displaying varying levels of posttraumatic stress symptoms and other psychopathology due to theories suggesting that resilience would prohibit posttraumatic growth. Few studies have examined growth amongst resilient people. The current study examined posttraumatic growth in a sample of sixty psychologically healthy people who experienced the Canterbury earthquake sequence of 2010-2011. The current study is a follow-up study that used thematic analysis to explore: (1) Whether posttraumatic growth is evident nine years after the Canterbury earthquake sequence and approximately six years after baseline assessment; and (2) What themes may facilitate the posttraumatic growth process in psychologically healthy people. Data were collected using semi-structured interviews. Thematic analysis revealed four themes describing participants’ experiences of growth: New possibilities, reappraisal of life and priorities, positive changes in self-perception and closer more meaningful relationships. Themes describing posttraumatic growth provide evidence for research question one. Thematic analysis revealed three main themes and multiple subthemes that may facilitate the process of growth in psychologically healthy people: Hardship, optimistic positive appraisal and people helping people. Themes describing processes that may lead to growth provide evidence for research question two. Results of the current study provide insights about the experience of growth in psychologically healthy people and cognitive and psychosocial factors that may facilitate growth in resilient individuals.
Though rare and unpredictable, earthquakes can and do cause catastrophic destruction when they impact unprepared and vulnerable communities. Extensive damage and failure of vulnerable buildings is a key factor which contributes to seismic-related disasters, making the proactive management of these buildings a necessity to reduce the risk of future disasters arising. The devastating Canterbury earthquakes of 2010 and 2011 brought the urgency of this issue to national importance in New Zealand. The national earthquake-prone building framework came into effect in 2017, obligating authorities to identify existing buildings with the greatest risk of collapse in strong earthquakes and for building owners to strengthen or demolish these buildings within a designated period of time. Though this framework is unique to New Zealand, the challenge of managing the seismic risk of such buildings is common amongst all seismically-active countries. Therefore, looking outward to examine how other jurisdictions legally manage this challenge is useful for reflecting on the approaches taken in New Zealand and understand potential lessons which could be adopted. This research compares the legal framework used to reduce the seismic risk of existing buildings in New Zealand with that of the similarly earthquake-prone countries of Japan and Italy. These legal frameworks are examined with a particular focus on the proactive goal of reducing risk and improving resilience, as is the goal of the international Sendai Framework for Disaster Risk Reduction 2015-2030. The Sendai Framework, which each of the case study countries have committed to and thus have obligations under, forms the legal basis of the need for states to reduce disaster risk in their jurisdictions. In particular, the states’ legal frameworks for existing building risk reduction are examined in the context of the Sendai priorities of understanding disaster risk, strengthening disaster risk governance, and investing in resilience. While this research illustrates that the case study countries have each adopted more proactive risk reduction frameworks in recent years in anticipation of future earthquakes, the frameworks currently focus on a very narrow range of existing buildings and thus are not currently sufficient for promoting the long-term resilience of building stocks. In order to improve resilience, it is argued, legal frameworks need to include a broader range of buildings subject to seismic risk reduction obligations and also to broaden the focus on long-term monitoring of potential risk to buildings.
A buckling-restrained braced frame (BRBF) is a structural bracing system that provides lateral strength and stiffness to buildings and bridges. They were first developed in Japan in the 1970s (Watanabe et al. 1973, Kimura et al. 1976) and gained rapid acceptance in the United States after the Northridge earthquake in 1994 (Bruneau et al. 2011). However, it was not until the Canterbury earthquakes of 2010/2011, that the New Zealand construction market saw a significant uptake in the use of buckling-restrained braces (BRBs) in commercial buildings (MacRae et al. 2015). In New Zealand there is not yet any documented guidance or specific instructions in regulatory standards for the design of BRBFs. This makes it difficult for engineers to anticipate all the possible stability and strength issues within a BRBF system and actively mitigate them in each design. To help ensure BRBF designs perform as intended, a peer review with physical testing are needed to gain building compliance in New Zealand. Physical testing should check the manufacturing and design of each BRB (prequalification testing), and the global strength and stability of each BRB its frame (subassemblage testing). However, the financial pressures inherent in commercial projects has led to prequalification testing (BRB only testing) being favoured without adequate design specific subassemblage testing. This means peer reviewers have to rely on BRB suppliers for assurances. This low regulation environment allows for a variety of BRBF designs to be constructed without being tested or well understood. The concern is that there may be designs that pose risk and that issues are being overlooked in design and review. To improve the safety and design of BRBFs in New Zealand, this dissertation studies the behaviour of BRBs and how they interact with other frame components. Presented is the experimental test process and results of five commercially available BRB designs (Chapter 2). It discusses the manufacturing process, testing conditions and limitations of observable information. It also emphasises that even though subassemblage testing is impractical, uniaxial testing of the BRB only is not enough, as this does not check global strength or stability. As an alternative to physical testing, this research uses computer simulation to model BRB behaviour. To overcome the traditional challenges of detailed BRB modelling, a strategy to simulate the performance of generic BRB designs was developed (Chapter 3). The development of nonlinear material and contact models are important aspects of this strategy. The Chaboche method is employed using a minimum of six backstress curves to characterize the combined isotropic and kinematic hardening exhibited by the steel core. A simplified approach, adequate for modelling the contact interaction between the restrainer and the core was found. Models also capture important frictional dissipation as well as lateral motion and bending associated with high order constrained buckling of the core. The experimental data from Chapter 2 was used to validate this strategy. As BRBs resist high compressive loading, global stability of the BRB and gusseted connection zone need to be considered. A separate study was conducted that investigated the yielding and buckling strength of gusset plates (Chapter 4). The stress distribution through a gusset plate is complex and difficult to predict because the cross-sectional area of gusset plate is not uniform, and each gusset plate design is unique in shape and size. This has motivated design methods that approximate yielding of gusset plates. Finite element modelling was used to study the development of yielding, buckling and plastic collapse behaviour of a brace end bolted to a series of corner gusset plates. In total 184 variations of gusset plate geometries were modelled in Abaqus®. The FEA modelling applied monotonic uniaxial load with an imperfection. Upon comparing results to current gusset plate design methods, it was found that the Whitmore width method for calculating the yield load of a gusset is generally un-conservative. To improve accuracy and safety in the design of gusset plates, modifications to current design methods for calculating the yield area and compressive strength for gusset plates is proposed. Bolted connections are a popular and common connection type used in BRBF design. Global out-of-plane stability tends to govern the design for this connection type with numerous studies highlighting the risk of instability initiated by inelasticity in the gussets, neck of the BRB end and/or restrainer ends. Subassemblage testing is the traditional method for evaluating global stability. However, physical testing of every BRBF variation is cost prohibitive. As such, Japan has developed an analytical approach to evaluate out-of-plane stability of BRBFs and incorporated this in their design codes. This analytical approach evaluates the different BRB components under possible collapse mechanisms by focusing on moment transfer between the restrainer and end of the BRB. The approach have led to strict criteria for BRBF design in Japan. Structural building design codes in New Zealand, Europe and the United States do not yet provide analytical methods to assess BRB and connection stability, with prototype/subassemblage testing still required as the primary means of accreditation. Therefore it is of interest to investigate the capability of this method to evaluate stability of BRBs designs and gusset plate designs used in New Zealand (including unstiffened gusset connection zones). Chapter 5 demonstrates the capability of FEA to study to the performance of a subassemblage test under cyclic loading – resembling that of a diagonal ground storey BRBF with bolted connections. A series of detailed models were developed using the strategy presented in Chapter 3. The geometric features of BRB 6.5a (Chapter 2) were used as a basis for the BRBs modelled. To capture the different failure mechanisms identified in Takeuchi et al. (2017), models varied the length that the cruciform (non-yielding) section inserts into the restrainer. Results indicate that gusset plates designed according to New Zealand’s Steel Structures Standard (NZS 3404) limit BRBF performance. Increasing the thickness of the gusset plates according to modifications discussed in Chapter 4, improved the overall performance for all variants (except when Lin/ Bcruc = 0.5). The effect of bi-directional loading was not found to notably affect out-of-plane stability. Results were compared against predictions made by the analytical method used in Japan (Takeuchi method). This method was found to be generally conservative is predicting out-of-plane stability of each BRBF model. Recommendations to improve the accuracy of Takeuchi’s method are also provided. The outcomes from this thesis should be helpful for BRB manufacturers, researchers, and in the development of further design guidance of BRBFs.
The overarching goal of this dissertation is to improve predictive capabilities of geotechnical seismic site response analyses by incorporating additional salient physical phenomena that influence site effects. Specifically, multidimensional wave-propagation effects that are neglected in conventional 1D site response analyses are incorporated by: (1) combining results of 3D regional-scale simulations with 1D nonlinear wave-propagation site response analysis, and (2) modelling soil heterogeneity in 2D site response analyses using spatially-correlated random fields to perturb soil properties. A method to combine results from 3D hybrid physics-based ground motion simulations with site-specific nonlinear site response analyses was developed. The 3D simulations capture 3D ground motion phenomena on a regional scale, while the 1D nonlinear site response, which is informed by detailed site-specific soil characterization data, can capture site effects more rigorously. Simulations of 11 moderate-to-large earthquakes from the 2010-2011 Canterbury Earthquake Sequence (CES) at 20 strong motion stations (SMS) were used to validate simulations with observed ground motions. The predictions were compared to those from an empirically-based ground motion model (GMM), and from 3D simulations with simplified VS30- based site effects modelling. By comparing all predictions to observations at seismic recording stations, it was found that the 3D physics-based simulations can predict ground motions with comparable bias and uncertainty as the GMM, albeit, with significantly lower bias at long periods. Additionally, the explicit modelling of nonlinear site-response improves predictions significantly compared to the simplified VS30-based approach for soft-soil or atypical sites that exhibit exceptionally strong site effects. A method to account for the spatial variability of soils and wave scattering in 2D site response analyses was developed and validated against a database of vertical array sites in California. The inputs required to run the 2D analyses are nominally the same as those required for 1D analyses (except for spatial correlation parameters), enabling easier adoption in practice. The first step was to create the platform and workflow, and to perform a sensitivity study involving 5,400 2D model realizations to investigate the influence of random field input parameters on wave scattering and site response. Boundary conditions were carefully assessed to understand their effect on the modelled response and select appropriate assumptions for use on a 2D model with lateral heterogeneities. Multiple ground-motion intensity measures (IMs) were analyzed to quantify the influence from random field input parameters and boundary conditions. It was found that this method is capable of scattering seismic waves and creating spatially-varying ground motions at the ground surface. The redistribution of ground-motion energy across wider frequency bands, and the scattering attenuation of high-frequency waves in 2D analyses, resemble features observed in empirical transfer functions (ETFs) computed in other studies. The developed 2D method was subsequently extended to more complicated multi-layer soil profiles and applied to a database of 21 vertical array sites in California to test its appropriate- ness for future predictions. Again, different boundary condition and input motion assumptions were explored to extend the method to the in-situ conditions of a vertical array (with a sensor embedded in the soil). ETFs were compared to theoretical transfer functions (TTFs) from conventional 1D analyses and 2D analyses with heterogeneity. Residuals of transfer-function- based IMs, and IMs of surface ground motions, were also used as validation metrics. The spatial variability of transfer-function-based IMs was estimated from 2D models and compared to the event-to-event variability from ETFs. This method was found capable of significantly improving predictions of median ETF amplification factors, especially for sites that display higher event-to-event variability. For sites that are well represented by 1D methods, the 2D approach can underpredict amplification factors at higher modes, suggesting that the level of heterogeneity may be over-represented by the 2D random field models used in this study.
A building boom in the 1980s allowed pre-stressed hollow-core floor construction to be widely adopted in New Zealand, even though the behaviour of these prefabricated elements within buildings was still uncertain. Inspections following the Canterbury and Kaikōura earthquakes has provided evidence of web-splitting, transverse cracking and longitudinal splitting on hollow-core units, confirming the susceptibility of these floors to undesirable failure modes. Hollow-core slabs are mainly designed to resist bending and shear. However, there are many applications in which they are also subjected to torsion. In New Zealand, hollow-core units contain no transverse reinforcement in the soffit concrete below the cells and no web reinforcement. Consequently, their dependable performance in torsion is limited to actions that they can resist before torsional cracking occurs. In previous work by the present authors, a three-dimensional FE modelling approach to study the shear flexural behaviour of precast pre-stressed hollow core units was developed and validated by full-scale experiments. This paper shows how the FE analyses have been extended to investigate the response of HC units subjected to torsional actions. Constitutive models, based on nonlinear fracture mechanics, have been used to numerically predict the torsional capacity of HC units and have been compared with experimental results. The results indicate that the numerical approach is promising and should be developed further as part of future research.
Observations of out-of-plane (OOP) instability in the 2010 Chile earthquake and in the 2011 Christchurch earthquake resulted in concerns about the current design provisions of structural walls. This mode of failure was previously observed in the experimental response of some wall specimens subjected to in-plane loading. Therefore, the postulations proposed for prediction of the limit states corresponding to OOP instability of rectangular walls are generally based on stability analysis under in-plane loading only. These approaches address stability of a cracked wall section when subjected to compression, thereby considering the level of residual strain developed in the reinforcement as the parameter that prevents timely crack closure of the wall section and induces stability failure. The New Zealand code requirements addressing the OOP instability of structural walls are based on the assumptions used in the literature and the analytical methods proposed for mathematical determination of the critical strain values. In this study, a parametric study is conducted using a numerical model capable of simulating OOP instability of rectangular walls to evaluate sensitivity of the OOP response of rectangular walls to variation of different parameters identified to be governing this failure mechanism. The effects of wall slenderness (unsupported height-to-thickness) ratio, longitudinal reinforcement ratio of the boundary regions and length on the OOP response of walls are evaluated. A clear trend was observed regarding the influence of these parameters on the initiation of OOP displacement, based on which simple equations are proposed for prediction of OOP instability in rectangular walls.
Major earthquakes, such as the Canterbury and Kaikoura events recorded in New Zealand in 2010 and 2016 respectively, highlighted that floor systems can be heavily damaged. At a reduced or full scale, quasi-static experimental tests on structural sub-assemblies can help to establish the seismic performance of structural systems. However, the experimental performance obtained with such tests is likely to be dependent on the drift protocol adopted. This paper provides an overview of the drift protocols which have been assumed in previous relevant experimental activities, with emphasis on those adopted for testing floor systems. The paper also describes the procedure used to define the loading protocol applied in the testing of a large precast concrete floor diaphragm as part of the Recast floor project at the University of Canterbury. Finally, major limits of current loading protocols, and areas of future research, are identified.
In the last two decades, New Zealand (NZ) has experienced significant earthquakes, including the 2010 M 7.2 Darfield, 2011 M 6.2 Christchurch, and 2016 M 7.8 Kaikōura events. Amongst these large events, tens of thousands of smaller earthquakes have occurred. While previous event and ground-motion databases have analyzed these events, many events below M 4 have gone undetected. The goal of this study is to expand on previous databases, particularly for small magnitude (M<4) and low-amplitude ground motions. This new database enables a greater understanding of regional variations within NZ and contributes to the validity of internationally developed ground-motion models. The database includes event locations and magnitude estimates with uncertainty considerations, and tectonic type assessed in a hierarchical manner. Ground motions are extracted from the GeoNet FDSN server and assessed for quality using a neural network classification approach. A deep neural network approach is also utilized for picking P and S phases for determination of event hypocentres. Relative hypocentres are further improved by double-difference relocation and will contribute toward developing shallow (< 50 km) seismic tomography models. Analysis of the resulting database is compared with previous studies for discussion of implications toward national hazard prediction models.
Floor systems with precast concrete hollow-core units have been largely used in concrete buildings built in New Zealand during the 1980’s. Recent earthquakes, such as the Canterbury sequence in 2010-2011 and the Kaikoura earthquake in 2016, highlighted that this floor system can be highly vulnerable and potentially lead to the floor collapse. A series of research activities are in progress to better understand the seismic performance of floor diaphragms, and this research focuses on examining the performance of hollow core units running parallel to the walls of wall-resisting concrete structures. This study first focused on the development of fragility functions, which can be quickly used to assess likelihood of the hollow-core being able to survive given the buildings design drift, and secondly to determine the expected performance of hollow-core units that run parallel to walls, focusing on the alpha unit running by the wall. Fragility functions are created for a range of different parameters for both vertical dislocation and crack width that can be used as the basis of a quick analysis or loss estimation for the likely impact of hollow-core floors on building vulnerability and risk. This was done using past experimental tests, and the recorded damage. Using these results and the method developed by Baker fragility curves were able to be created for varying crack widths and vertical dislocations. Current guidelines for analysis of hollow-core unit incompatible displacements are based on experimental vertical displacement results from concrete moment resisting frame systems to determine the capacity of hollow-core elements. To investigate the demands on hollow-core units in a wall-based structure, a fibre-element model in the software Seismostruct is created and subject to quasi-static cyclic loading, using elements which are verified from previous experimental tests. It is shown that for hollow-core units running by walls that the 10 mm displacement capacity used for hollow-core units running by a beam is insufficient for members running by walls and that shear analysis should be used. The fibre-element model is used to simulate the seismic demand induced on the floor system and has shown that the shear demand is a function of drift, wall length, hollow-core span, linking slab length and, to a minor extent, wall elongation.
In major seismic events, a number of plan-asymmetric buildings which experienced element failure or structural collapse had twisted significantly about their vertical axis during the earthquake shaking. This twist, known as “building torsion”, results in greater demands on one side of a structure than on the other side. The Canterbury Earthquakes Royal Commission’s reports describe the response of a number of buildings in the February 2011 Christchurch earthquakes. As a result of the catastrophic collapse of one multi-storey building with significant torsional irregularity, and significant torsional effects also in other buildings, the Royal Commission recommended that further studies be undertaken to develop improved simple and effective guides to consider torsional effects in buildings which respond inelastically during earthquake shaking. Separately from this, as building owners, the government, and other stakeholders, are planning for possible earthquake scenarios, they need good estimates of the likely performance of both new and existing buildings. These estimates, often made using performance based earthquake engineering considerations and loss estimation techniques, inform decision making. Since all buildings may experience torsion to some extent, and torsional effects can influence demands on building structural and non-structural elements, it is crucial that demand estimates consider torsion. Building seismic response considering torsion can be evaluated with nonlinear time history analysis. However, such analysis involves significant computational effort, expertise and cost. Therefore, from an engineers’ point of view, simpler analysis methods, with reasonable accuracy, are beneficial. The consideration of torsion in simple analysis methods has been investigated by many researchers. However, many studies are theoretical without direct relevance to structural design/assessment. Some existing methods also have limited applicability, or they are difficult to use in routine design office practice. In addition, there has been no consensus about which method is best. As a result, there is a notable lack of recommendations in current building design codes for torsion of buildings that respond inelastically. There is a need for building torsion to be considered in yielding structures, and for simple guidance to be developed and adopted into building design standards. This study aims to undertaken to address this need for plan-asymmetric structures which are regular over their height. Time history analyses are first conducted to quantify the effects of building plan irregularity, that lead to torsional response, on the seismic response of building structures. Effects of some key structural and ground motion characteristics (e.g. hysteretic model, ground motion duration, etc.) are considered. Mass eccentricity is found to result in rather smaller torsional response compared to stiffness/strength eccentricity. Mass rotational inertia generally decreases the torsional response; however, the trend is not clearly defined for torsionally restrained systems (i.e. large λty). Systems with EPP and bilinear models have close displacements and systems with Takeda, SINA, and flag-shaped models yield almost the same displacements. Damping has no specific effect on the torsional response for the single-storey systems with the unidirectional eccentricity and excitation. Displacements of the single-storey systems subject to long duration ground motion records are smaller than those for short duration records. A method to consider torsional response of ductile building structures under earthquake shaking is then developed based on structural dynamics for a wide range of structural systems and configurations, including those with low and high torsional restraint. The method is then simplified for use in engineering practice. A novel method is also proposed to simply account for the effects of strength eccentricity on response of highly inelastic systems. A comparison of the accuracy of some existing methods (including code-base equivalent static method and model response spectrum analysis method), and the proposed method, is conducted for single-storey structures. It is shown that the proposed method generally provides better accuracy over a wide range of parameters. In general, the equivalent static method is not adequate in capturing the torsional effects and the elastic modal response spectrum analysis method is generally adequate for some common parameters. Record-to-record variation in maximum displacement demand on the structures with different degrees of torsional response is considered in a simple way. Bidirectional torsional response is then considered. Bidirectional eccentricity and excitation has varying effects on the torsional response; however, it generally increases the weak and strong edges displacements. The proposed method is then generalized to consider the bidirectional torsion due to bidirectional stiffness/strength eccentricity and bidirectional seismic excitation. The method is shown to predict displacements conservatively; however, the conservatism decreases slightly for cases with bidirectional excitation compared to those subject to unidirectional excitation. In is shown that the roof displacement of multi-storey structures with torsional response can be predicted by considering the first mode of vibration. The method is then further generalized to estimate torsional effects on multi-storey structure displacement demands. The proposed procedure is tested multi-storey structures and shown to predict the displacements with a good accuracy and conservatively. For buildings which twist in plan during earthquake shaking, the effect of P-Δλ action is evaluated and recommendations for design are made. P-Δλ has more significant effects on systems with small post- yield stiffness. Therefore, system stability coefficient is shown not to be the best indicator of the importance of P-Δλ and it is recommended to use post-yield stiffness of system computed with allowance for P-Δλ effects. For systems with torsional response, the global system stability coefficient and post- yield stiffness ration do not reflect the significance of P-Δλ effects properly. Therefore, for torsional systems individual seismic force resisting systems should be considered. Accuracy of MRSA is investigated and it is found that the MRSA is not always conservative for estimating the centre of mass and strong edge displacements as well as displacements of ductile systems with strength eccentricity larger than stiffness eccentricity. Some modifications are proposed to get the MRSA yields a conservative estimation of displacement demands for all cases.
These research papers explore the concept of vulnerability in international human rights law. In the wake of the Christchurch earthquakes of 2010-2011, this research focuses on how "vulnerability" has been used and developed within the wider human rights discourse. They also examine jurisprudence of international human rights bodies, and how the concept of "vulnerability" has been applied. The research also includes a brief investigation into the experiences of vulnerable populations in disaster contexts, focusing primarily on the experiences of "vulnerable persons" in the Christchurch earthquakes and their aftermath.
These research papers explore the concept of vulnerability in international human rights law. In the wake of the Christchurch earthquakes of 2010-2011, this research focuses on how "vulnerability" has been used and developed within the wider human rights discourse. They also examine jurisprudence of international human rights bodies, and how the concept of "vulnerability" has been applied. The research also includes a brief investigation into the experiences of vulnerable populations in disaster contexts, focusing primarily on the experiences of "vulnerable persons" in the Christchurch earthquakes and their aftermath.
In response to the February 2011 earthquake, Parliament enacted the Canterbury Earthquake Recovery Act. This emergency legislation provided the executive with extreme powers that extended well beyond the initial emergency response and into the recovery phase. Although New Zealand has the Civil Defence Emergency Management Act 2002, it was unable to cope with the scale and intensity of the Canterbury earthquake sequence. Considering the well-known geological risk facing the Wellington region, this paper will consider whether a standalone “Disaster Recovery Act” should be established to separate an emergency and its response from the recovery phase. Currently, Government policy is to respond reactively to a disaster rather than proactively. In a major event, this typically involves the executive being given the ability to make rules, regulations and policy without the delay or oversight of normal legislative process. In the first part of this paper, I will canvas what a “Disaster Recovery Act” could prescribe and why there is a need to separate recovery from emergency. Secondly, I will consider the shortfalls in the current civil defence recovery framework which necessitates this kind of heavy governmental response after a disaster. In the final section, I will examine how
These research papers explore the concept of vulnerability in international human rights law. In the wake of the Christchurch earthquakes of 2010-2011, this research focuses on how "vulnerability" has been used and developed within the wider human rights discourse. They also examine jurisprudence of international human rights bodies, and how the concept of "vulnerability" has been applied. The research also includes a brief investigation into the experiences of vulnerable populations in disaster contexts, focusing primarily on the experiences of "vulnerable persons" in the Christchurch earthquakes and their aftermath.
This study investigates the uncertainty of simulated earthquake ground motions for smallmagnitude events (Mw 3.5 – 5) in Canterbury, New Zealand. 148 events were simulated with specified uncertainties in: event magnitude, hypocentre location, focal mechanism, high frequency rupture velocity, Brune stress parameter, the site 30-m time-averaged shear wave velocity (Vs30), anelastic attenuation (Q) and high frequency path duration. In order to capture these uncertainties, 25 realisations for each event were generated using the Graves and Pitarka (2015) hybrid broadband simulation approach. Monte-Carlo realisations were drawn from distributions for each uncertainty, to generate a suite of simulation realisations for each event and site. The fit of the multiple simulation realisations to observations were assessed using linear mixed effects regression to generate the systematic source, path and site effects components across all ground motion intensity measure residuals. Findings show that additional uncertainties are required in each of the three source, path, and site components, however the level of output uncertainty is promising considering the input uncertainties included.
This study analyses the success and limitations of the recovery process following the 2010–11 earthquake sequence in Christchurch, New Zealand. Data were obtained from in-depth interviews with 32 relocated households in Christchurch, and from a review of recovery policies implemented by the government. A top-down approach to disaster recovery was evident, with the creation of multiple government agencies and processes that made grassroots input into decision-making difficult. Although insurance proceeds enabled the repair and rebuilding of many dwellings, the complexity and adversarial nature of the claim procedures also impaired recovery. Householders’ perceptions of recovery reflected key aspects of their post-earthquake experiences (e.g. the housing offer they received, and the negotiations involved), and the outcomes of their relocation (including the value of the new home, their subjective well-being, and lifestyle after relocation). Protracted insurance negotiations, unfair offers and hardships in post-earthquake life were major challenges to recovery. Less-thanfavourable recovery experiences also transformed patterns of trust in local communities, as relocated householders came to doubt both the government and private insurance companies’ ability to successfully manage a disaster. At the same time, many relocated households expressed trust in their neighbours and communities. This study illuminates how government policies influence disaster recovery while also suggesting a need to reconsider centralised, top-down approaches to managing recovery.
Abstract. Natural (e.g., earthquake, flood, wildfires) and human-made (e.g., terrorism, civil strife) disasters are inevitable, can cause extensive disruption, and produce chronic and disabling psychological injuries leading to formal diagnoses (e.g., post-traumatic stress disorder [PTSD]). Following natural disasters of earthquake (Christchurch, Aotearoa/New Zealand, 2010–11) and flood (Calgary, Canada, 2013), controlled research showed statistically and clinically significant reductions in psychological distress for survivors who consumed minerals and vitamins (micronutrients) in the following months. Following a mass shooting in Christchurch (March 15, 2019), where a gunman entered mosques during Friday prayers and killed and injured many people, micronutrients were offered to survivors as a clinical service based on translational science principles and adapted to be culturally appropriate. In this first translational science study in the area of nutrition and disasters, clinical results were reported for 24 clients who completed the Impact of Event Scale – Revised (IES-R), the Depression Anxiety Stress Scales (DASS), and the Modified-Clinical Global Impression (M-CGI-I). The findings clearly replicated prior controlled research. The IES-R Cohen’s d ESs were 1.1 (earthquake), 1.2 (flood), and 1.13 (massacre). Effect sizes (ESs) for the DASS subscales were also consistently positive across all three events. The M-CGI-I identified 58% of the survivors as “responders” (i.e., self-reported as “much” to “very much” improved), in line with those reported in the earthquake (42%) and flood (57%) randomized controlled trials, and PTSD risk reduced from 75% to 17%. Given ease of use and large ESs, this evidence supports the routine use of micronutrients by disaster survivors as part of governmental response.