Asset management in power systems is exercised to improve network reliability to provide confidence and security for customers and asset owners. While there are well-established reliability metrics that are used to measure and manage business-as-usual disruptions, an increasing appreciation of the consequences of low-probability high-impact events means that resilience is increasingly being factored into asset management in order to provide robustness and redundancy to components and wider networks. This is particularly important for electricity systems, given that a range of other infrastructure lifelines depend upon their operation. The 2010-2011 Canterbury Earthquake Sequence provides valuable insights into electricity system criticality and resilience in the face of severe earthquake impacts. While above-ground assets are relatively easy to monitor and repair, underground assets such as cables emplaced across wide areas in the distribution network are difficult to monitor, identify faults on, and repair. This study has characterised in detail the impacts to buried electricity cables in Christchurch resulting from seismically-induced ground deformation caused primarily by liquefaction and lateral spread. Primary modes of failure include cable bending, stretching, insulation damage, joint braking and, being pulled off other equipment such as substation connections. Performance and repair data have been compiled into a detailed geospatial database, which in combination with spatial models of peak ground acceleration, peak ground velocity and ground deformation, will be used to establish rigorous relationships between seismicity and performance. These metrics will be used to inform asset owners of network performance in future earthquakes, further assess component criticality, and provide resilience metrics.
In the last two decades, the retail sector has experienced unprecedented upheaval, having severe implications for economic development and sustenance of traditional inner-city retail districts. In the city of Christchurch, New Zealand, this effect has been exacerbated by a series of earthquakes in 2010/2011 which destroyed much of the traditional retail precinct of the city. After extensive rebuild activity of the city’s infrastructure, the momentum of retailers returning to the inner city was initially sluggish but eventually gathered speed supported by increased international visitation. In early 2020, the return to retail normality came to an abrupt halt after the emergence of the COVID-19 pandemic. This study uses spending and transaction data to analyze the compounding impact of the earthquake’s aftermath, shift to online shopping, and the retail disruption in the Christchurch central retail precinct because of COVID-19. The findings illustrate how consumers through their spending respond to different types of external shocks, altering their consumption patterns and retail mode (offline and online) to cope with an ever-changing retail landscape. Each event triggers different spending patterns that have some similarities but also stark differences, having implications for a sustainable and resilient retail industry in Christchurch. Implications for urban retail precinct development are also discussed.
Geologic phenomena produced by earthquake shaking, including rockfalls and liquefaction features, provide important information on the intensity and spatiotemporal distribution of earthquake ground motions. The study of rockfall and liquefaction features produced in contemporary well- instrumented earthquakes increases our knowledge of how natural and anthropogenic environments respond to earthquakes and improves our ability to deduce seismologic information from analogous pre-contemporary (paleo-) geologic features. The study of contemporary and paleo- rockfall and liquefaction features enables improved forecasting of environmental responses to future earthquakes. In this thesis I utilize a combination of field and imagery-based mapping, trenching, stratigraphy, and numerical dating techniques to understand the nature and timing of rockfalls (and hillslope sedimentation) and liquefaction in the eastern South Island of New Zealand, and to examine the influence that anthropogenic activity has had on the geologic expressions of earthquake phenomena. At Rapaki (Banks Peninsula, NZ), field and imagery-based mapping, statistical analysis and numerical modeling was conducted on rockfall boulders triggered by the fatal 2011 Christchurch earthquakes (n=285) and compared with newly identified prehistoric (Holocene and Pleistocene) boulders (n=1049) deposited on the same hillslope. A significant population of modern boulders (n=26) travelled farther downslope (>150 m) than their most-travelled prehistoric counterparts, causing extensive damage to residential dwellings at the foot of the hillslope. Replication of prehistoric boulder distributions using 3-dimensional rigid body numerical models requires the application of a drag-coefficient, attributed to moderate to dense slope vegetation, to account for their spatial distribution. Radiocarbon dating provides evidence for 17th to early 20th century deforestation at the study site during Polynesian and European colonization and after emplacement of prehistoric rockfalls. Anthropocene deforestation enabled modern rockfalls to exceed the limits of their prehistoric predecessors, highlighting a shift in the geologic expression of rockfalls due to anthropogenic activity. Optical and radiocarbon dating of loessic hillslope sediments in New Zealand’s South Island is used to constrain the timing of prehistoric rockfalls and associated seismic events, and quantify spatial and temporal patterns of hillslope sedimentation including responses to seismic and anthropogenic forcing. Luminescence ages from loessic sediments constrain timing of boulder emplacement to between ~3.0 and ~12.5 ka, well before the arrival of Polynesians (ca AD 1280) and Europeans (ca AD 1800) in New Zealand, and suggest loess accumulation was continuing at the study site until 12-13 ka. Large (>5 m3) prehistoric rockfall boulders preserve an important record of Holocene hillslope sedimentation by creating local traps for sediment aggradation and upbuilding soil formation. Sediment accumulation rates increased considerably (>~10 factor increase) following human arrival and associated anthropogenic burning of hillslope vegetation. New numerical ages are presented to place the evolution of loess-mantled hillslopes in New Zealand’s South Island into a longer temporal framework and highlight the roles of earthquakes and humans on hillslope surface process. Extensive field mapping and characterization for 1733 individual prehistoric rockfall boulders was conducted at Rapaki and another Banks Peninsula site, Purau, to understand their origin, frequency, and spatial and volumetric distributions. Boulder characteristics and distributions were compared to 421 boulders deposited at the same sites during the 2010-2011 Canterbury earthquake sequence. Prehistoric boulders at Rapaki and Purau are comprised of two dominant lithofacies types: volcanic breccia and massive (coherent) lava basalt. Volcanic breccia boulders are found in greatest abundance (64-73% of total mapped rockfall) and volume (~90-96% of total rockfall) at both locations and exclusively comprise the largest boulders with the longest runout distances that pose the greatest hazard to life and property. This study highlights the primary influence that volcanic lithofacies architecture has on rockfall hazard. The influence of anthropogenic modifications on the surface and subsurface geologic expression of contemporary liquefaction created during the 2010-2011 Canterbury earthquake sequence (CES) in eastern Christchurch is examined. Trench observations indicate that anthropogenic fill layer boundaries and the composition/texture of discretely placed fill layers play an important role in absorbing fluidized sand/silt and controlling the subsurface architecture of preserved liquefaction features. Surface liquefaction morphologies (i.e. sand blows and linear sand blow arrays) display alignment with existing utility lines and utility excavations (and perforated pipes) provided conduits for liquefaction ejecta during the CES. No evidence of pre-CES liquefaction was identified within the anthropogenic fill layers or underlying native sediment. Radiocarbon dating of charcoal within the youngest native sediment suggests liquefaction has not occurred at the study site for at least the past 750-800 years. The importance of systematically examining the impact of buried infrastructure on channelizing and influencing surface and subsurface liquefaction morphologies is demonstrated. This thesis highlights the importance of using a multi-technique approach for understanding prehistoric and contemporary earthquake phenomena and emphasizes the critical role that humans play in shaping the geologic record and Earth’s surface processes.
Terminus calving of icebergs is a common mass-loss mechanism from water-terminating glaciers globally, including the lake-calving glaciers in New Zealand’s central Southern Alps. Calving rates can increase dramatically in response to increases in ice velocity and/or retreat of the glacier margin. Here, we describe a large calving event (c. 4.5 × 106 m3) observed at Tasman Glacier, which initiated around 30 min after the MW 6.2 Christchurch earthquake of 22 February 2011. The volume of this calving event was equalled or exceeded only once in a subsequent 13-month-long study. While the temporal association with the earthquake remains intriguing, the effects of any preconditioning factors remain unclear.
It is well established that urban green areas provide a wide range of social, aesthetic, environmental and economic benefits. The importance of urban green spaces has been known for decades; however the relationship between urban livability and green areas, as incorporated in overall urban green structure, has become the focus of international studies during the last 10 to 15 years. The spatial structure of green space systems has important consequences for urban form; configuring urban resources, controlling urban size, improving ecological quality of urban areas and preventing or mitigating natural disasters. However, in the field of architecture or urban design, very little work has been done to investigate the potential for built form to define and differentiate the edge to a green corridor ... This thesis therefore poses the hypothesis that architecture and urban design critically mediate between city and green corridor, through intensification and definition of the built edge, as a means of contributing to an ecological city form.
Christchurch Ōtautahi, New Zealand, is a city of myriad waterways and springs. Māori, the indigenous people of New Zealand, have water quality at the core of their cultural values. The city’s rivers include the Avon/Ōtākaro, central to the city centre’s aesthetic appeal since early settlement, and the Heathcote/Ōpāwaho. Both have been degraded with increasing urbanisation. The destructive earthquake sequence that occurred during 2010/11 presented an opportunity to rebuild significant areas of the city. Public consultation identified enthusiasm to rebuild a sustainable city. A sustainable water sensitive city is one where development is constructed with the water environment in mind. Water sensitive urban design applies at all scales and is a holistic concept. In Christchurch larger-scale multi-value stormwater management solutions were incorporated into rapidly developed greenfield sites on the city’s outskirts and in satellite towns, as they had been pre-earthquake. Individual properties on greenfield sites and within the city, however, continued to be constructed without water sensitive features such as rainwater tanks or living roofs. This research uses semi-structured interviews, policy analysis, and findings from local and international studies to investigate the benefits of building-scale WSUD and the barriers that have resulted in their absence. Although several inter-related barriers became apparent, cost, commonly cited as a barrier to sustainable development in general, was strongly represented. However, it is argued that the issue is one of mindset rather than cost. Solutions are proposed, based on international and national experience, that will demonstrate the benefits of adopting water sensitive urban design principles including at the building scale, and thereby build public and political support. The research is timely - there is still much development to occur, and increasing pressures from urban densification, population growth and climate change to mitigate.
Recent earthquakes in New Zealand proved that a shift is necessary in the current design practice of structures to achieve better seismic performance. Following such events, the number of new buildings using innovative technical solutions (e.g. base isolation, controlled rocking systems, damping devices, etc.), has increased, especially in Christchurch. However, the application of these innovative technologies is often restricted to medium-high rise buildings due to the maximum benefit to cost ratio. In this context, to address this issue, a multi-disciplinary geo-structural-environmental engineering project funded by the Ministry of Business Innovation and Employment (MBIE) is being carried out at the University of Canterbury. The project aims at developing a foundation system which will improve the seismic performance of medium-density low-rise buildings. Such foundation is characterized by two main elements: 1) granulated tyre rubber mixed with gravelly soils to be placed beneath the structure, with the goal of damping part of the seismic energy before it reaches the superstructure; and 2) a basement raft made of steel-fibre rubberised concrete to enhance the flexibility of the foundation under differential displacement demand. In the first part of this paper, the overarching objectives, scope and methodology of the project will be briefly described. Then, preliminary findings on the materials characterization, i.e., the gravel-rubber mixtures and steel-fibre rubberised concrete mixes, will be presented and discussed with focus on the mechanical behaviour.
Following the recent earthquakes in Chile (2010) and New Zealand (2010/2011), peculiar failure modes were observed in Reinforced Concrete (RC) walls. These observations have raised a global concern on the contribution of bi-directional loading to these failure mechanisms. One of the failure modes that could potentially result from bidirectional excitations is out-of-plane shear failure. In this paper an overview of the recent experimental and numerical findings regarding out-of-plane shear failure in RC walls are presented. The numerical study presents the Finite Element (FE) simulation of wall D5-6 from the Grand Chancellor Hotel that failed in shear in the out-of-plane direction in the February 2011 Christchurch earthquake. The main objective of the numerical study was to investigate the reasons for this failure mode. The experimental campaign includes the recent experiments conducted in the Structural Engineering Laboratory of the University of Canterbury. The experimental study included three rectangular slender RC walls designed based on NZS3101: 2006-A3 (2017) for three different ductility levels, namely: nominally ductile, limited ductile and ductile. The numerical results showed that high axial load combined with bi-directional loading caused the out-of-plane shear failure in wall D5-6 from the Grand Chancellor Hotel. This was also confirmed and further investigated in the experimental phase of the study.
The skills agenda has grown in prominence within the construction industry. Indeed, skill shortages have been recognised as a perennial problem the construction industry faces, especially after a major disaster. In the aftermath of the Christchurch earthquakes, small and medium construction companies were at the forefront of rebuilding efforts. While the survival of these companies was seen to be paramount, and extreme events were seen to be a threat to survival, there is a dearth of research centring on their resourcing capacity following a disaster. This research aims to develop workforce resourcing best practice guidelines for subcontractors in response to large disaster reconstruction demands. By using case study methods, this research identified the challenges faced by subcontracting businesses in resourcing Christchurch recovery projects; identified the workforce resourcing strategies adopted by subcontracting businesses in response to reconstruction demand; and developed a best practice guideline for subcontracting businesses in managing the workforce at the organisational and/or project level. This research offers a twofold contribution. First, it provides an overview of workforce resourcing practices in subcontracting businesses. This understanding has enabled the development of a more practical workforce resourcing guideline for subcontractors. Second, it promotes evidence-informed decision-making in subcontractors’ workforce resourcing. Dynamics in workforce resourcing and their multifaceted interactions were explicitly depicted in this research. More importantly, this research provides a framework to guide policy development in producing a sustainable solution to skill shortages and establishing longterm national skill development initiatives. Taken together, this research derives a research agenda that maps under-explored areas relevant for further elaboration and future research. Prospective researchers can use the research results in identifying gaps and priority areas in relation to workforce resourcing.
Unreinforced masonry (URM) cavity-wall construction is a form of masonry where two leaves of clay brick masonry are separated by a continuous air cavity and are interconnected using some form of tie system. A brief historical introduction is followed by details of a survey undertaken to determine the prevalence of URM cavity-wall buildings in New Zealand. Following the 2010/2011 Canterbury earthquakes it was observed that URM cavity-walls generally suffered irreparable damage due to a lack of effective wall restraint and deficient cavity-tie connections, combined with weak mortar strength. It was found that the original cavity-ties were typically corroded due to moisture ingress, resulting in decreased lateral loadbearing capacity of the cavity-walls. Using photographic data pertaining to Christchurch URM buildings that were obtained during post-earthquake reconnaissance, 252 cavity-walls were identified and utilised to study typical construction details and seismic performance. The majority (72%, 182) of the observed damage to URM cavity-wall construction was a result of out-of-plane type wall failures. Three types of out-of-plane wall failure were recognised: (1) overturning response, (2) one-way bending, and (3) two-way bending. In-plane damage was less widely observed (28%) and commonly included diagonal shear cracking through mortar bed joints or bricks. The collected data was used to develop an overview of the most commonly-encountered construction details and to identify typical deficiencies in earthquake response that can be addressed via the selection and implementation of appropriate mitigation interventions. http://www.journals.elsevier.com/structures
In February of 2011, an earthquake destroyed the only all-weather athletics track in the city of Christchurch (New Zealand). The track has yet to be replaced, and so since the loss of the track, local Christchurch athletes have only had a grass track for training and preparation for championship events. This paper considers what effect the loss of the training facility has had on the performance of athletes from Christchurch at national championship events. Not surprisingly, the paper finds that there has been a deterioration in the performance in events that are heavily dependent upon the all-weather surface. However, somewhat more surprisingly, the loss of the track appears to have caused a significant improvement in the performance of Christchurch athletes in events that, while on the standard athletics program, are not heavily track dependent.
The focus of this paper is to identify potential benefits of community involvement in master planning in the post-earthquake recovery context in Christchurch; and to identify considerations for planners involved in the design of master planning processes that involve the community. Findings are based on the results of an information sharing event on these topics convened by The Habitat Project in December 2011, and a review of the relevant literature.
- The Avon-Ōtākaro Redzone is an 11 kilometer stretch of land along the Avon-Ōtākaro River in Christchurch. - This project focused on the creation of a publicly available biodiversity map of the AvonŌtākaro River Corridor, a project undertaken as part of the ecological restoration of the Christchurch redzone. - This project originated from the Christchurch 2010-2011 earthquake sequence which saw liquefaction damage along 11km of the Avon River. Under guidance from The Nature Lab & Ōtākaro Living Laboratory, and various other experts, the primary research objective was to map historical biodiversity, identify hotspots, and assess areas for potential revegetation. - The data collected came from historical black maps, current iNaturalist data, and soil classification information. - The findings show that, pre-colonialism, the area was composed of herbaceous areas, wetlands, native shrubland, and tussock land, with key plants such as river, fern, tutu, and cabbage trees. - The post-earthquake analysis shows a transition from a residential area to patchy grasslands and swampy areas. - The findings also showed a strong relationship between historic sites and soil classifications, providing knowledge for past and future vegetation patterns and spread. - This map will be a valuable resource for conservation efforts and public engagement as the area transitions into a blue-green corridor.
At the conclusion of the 2010 and 2011 Canterbury earthquakes more than 5100 homes had been deemed unsafe for habitation. The land and buildings of these were labelled “red zoned” and are too badly damaged for remediation. These homes have been demolished or are destined for demolition. To assist the red zone population to relocate, central government have offered to ‘buy out’ home owners at the Governmental Value (GV) that was last reviewed in 2007. While generous in the economic context at the time, the area affected was the lowest value land and housing in Christchurch and so there is a capital shortfall between the 2007 property value and the cost of relocating to more expensive properties. This shortfall is made worse by increasing present day values since the earthquakes. Red zone residents have had to relocate to the far North and Western extremities of Christchurch, and some chose to move even further to neighbouring towns or cities. The eastern areas and commercial centres close to the red zone are affected as well. They have lost critical mass which has negatively impacted businesses in the catchments of the Red Zone. This thesis aims to repopulate the suburbs most affected by the abandonment of the red zone houses. Because of the relative scarcity of sound building sites in the East and to introduce affordability to these houses, an alternative method of development is required than the existing low density suburban model. Smart medium density design will be tested as an affordable and appropriate means of living. Existing knowledge in this field will be reviewed, an analysis of what East Christchurch’s key characteristics are will occur, and an examination of built works and site investigations will also be conducted. The research finds that at housing densities of 40 units per hectare, the spatial, vehicle, aesthetic needs of East Christchurch can be accommodated. Centralising development is also found to offer better lifestyle choices than the isolated suburbs at the edges of Christchurch, to be more efficient using existing infrastructure, and to place less reliance on cars. Stronger communities are formed from the outset and for a full range of demographics. Eastern affordable housing options are realised and Christchurch’s ever expanding suburban tendencies are addressed. East Christchurch presently displays a gaping scar of devastated houses that ‘The New Eastside’ provides a bandage and a cure for. Displaced and dispossessed Christchurch residents can be re-housed within a new heart for East Christchurch.
When the devastating 6.3 magnitude earthquake hit Christchurch, Aotearoa New Zealand, at 12.51pm on 22nd February 2011, the psychological and physical landscape was irrevocably changed. In the days and weeks following the disaster communities were isolated due to failed infrastructure, continuing aftershocks and the extensive search and rescue effort which focussed resources on the central business district. In such moments the resilience of a community is truly tested. This research discusses the role of grassroots community groups in facilitating community resilience during the Christchurch 2010/11 earthquakes and the role of place in doing so. I argue that place specific strategies for urban resilience need to be enacted from a grassroots level while being supported by broader policies and agencies. Using a case study of Project Lyttelton – a group aspiring towards a resilient sustainable future who were caught at the epicentre of the February earthquake – I demonstrate the role of a community group in creating resilience through self-organised place specific action during a disaster. The group provided emotional care, basic facilities and rebuilding assistance to the residents of Lyttelton, proving to be an invaluable asset. These actions are closely linked to the characteristics of social support and social learning that have been identified as important to socio-ecological resilience. In addition this research will seek to understand and explore the nuances of place and identity and its role in shaping resilience to such dis-placing events. Drawing on community narratives of the displacement of place identity, the potential for a progressive sense of place as instigated by local groups will be investigated as an avenue for adaptation by communities at risk of disaster and place destabilisation.
Rapid, accurate structural health monitoring (SHM) assesses damage to optimise decision-making. Many SHM methods are designed to track nonlinear stiffness changes as damage. However, highly nonlinear pinched hysteretic systems are problematic in SHM. Model-based SHM often fails as any mismatch between model and measured response dynamics leads to significant error. Thus, modelfree methods of hysteresis loop tracking methods have emerged. This study compares the robustness and accuracy in the presence of significant measurement noise of the proven hysteresis loop analysis (HLA) SHM method with 3 emerging model-free methods and 2 further novel adaptations of these methods using a highly nonlinear, 6-story numerical structure to provide a known ground-truth. Mean absolute errors in identifying a known nonlinear stiffness trajectory assessed at four points over two successive ground motion inputs from September 2010 and February 2011 in Christchurch range from 1.71-10.52%. However, the variability is far wider with maximum errors ranging from 3.90-49.72%, where the second largest maximum absolute error was still 19.74%. The lowest mean and maximum absolute errors were for the HLA method. The next best method had mean absolute error of 2.92% and a maximum of 10.51%. These results show the clear superiority of the HLA method over all current emerging model-free methods designed to manage the highly nonlinear pinching responses common in reinforced concrete structures. These results, combined with high robustness and accuracy in scaled and fullscale experimental studies, provide further validation for using HLA for practical implementation.
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.
Despite their good performance in terms of their design objectives, many modern code-prescriptive buildings built in Christchurch, New Zealand had to be razed after the 2010-2011 Canterbury earthquakes because repairs were deemed too costly due to widespread sacrificial damage. Clearly a more effective design paradigm is needed to create more resilient structures. Rocking, post-tensioned connections with supplemental energy dissipation can contribute to a damage avoidance designs (DAD). However, few have achieved all three key design objectives of damage-resistant rocking, inherent recentering ability, and repeatable, damage-free energy dissipation for all cycles, which together offer a response which is independent of loading history. Results of experimental tests are presented for a near full-scale rocking beam-column sub-assemblage. A matrix of test results is presented for the system under varying levels of posttensioning, with and without supplemental dampers. Importantly, this parametric study delineates each contribution to response. Practical limitations on posttensioning are identified: a minimum to ensure static structural re-centering, and a maximum to ensure deformability without threadbar yielding. Good agreement between a mechanistic model and experimental results over all parameters and inputs indicates the model is robust and accurate for design. The overall results indicate that it is possible to create a DAD connection where the non-linear force-deformation response is loading history independent and repeatable over numerous loading cycles, without damage, creating the opportunity for the design and implementation of highly resilient structures.
Capacity design and hierarchy of strength philosophies at the base of modern seismic codes allow inelastic response in case of severe earthquakes and thus, in most traditional systems, damage develops at well-defined locations of reinforced concrete (RC) structures, known as plastic hinges. The 2010 and 2011 Christchurch earthquakes have demonstrated that this philosophy worked as expected. Plastic hinges formed in beams, in coupling beams and at the base of columns and walls. Structures were damaged permanently, but did not collapse. The 2010 and 2011 Christchurch earthquakes also highlighted a critical issue: the reparability of damaged buildings. No methodologies or techniques were available to estimate the level of subsequent earthquakes that RC buildings could still sustain before collapse. No repair techniques capable of restoring the initial condition of buildings were known. Finally, the cost-effectiveness of an eventual repair intervention, when compared with a new building, was unknown. These aspects, added to nuances of New Zealand building owners’ insurance coverage, encouraged the demolition of many buildings. Moreover, there was a perceived strong demand from government and industry to develop techniques for assessing damage to steel reinforcement bars embedded in cracked structural concrete elements. The most common questions were: “Have the steel bars been damaged in correspondence to the concrete cracks?”, “How much plastic deformation have the steel bars undergone?”, and “What is the residual strain capacity of the damaged bars?” Minimally invasive techniques capable of quantifying the level and extent of plastic deformation and residual strain capacity are not yet available. Although some studies had been recently conducted, a validated method is yet to be widely accepted. In this thesis, a least-invasive method for the damage-assessment of steel reinforcement is developed. Based on the information obtained from hardness testing and a single tensile test, it is possible to estimate the mechanical properties of earthquake-damaged rebars. The reduction in the low-cycle fatigue life due to strain ageing is also quantified. The proposed damage assessment methodology is based on empirical relationships between hardness and strain and residual strain capacity. If damage is suspected from in situ measurements, visual inspection or computer analysis, a bar may be removed and more accurate hardness measurements can be obtained using the lab-based Vickers hardness methodology. The Vickers hardness profile of damaged bars is then compared with calibration curves (Vickers hardness versus strain and residual strain capacity) previously developed for similar steel reinforcement bars extracted from undamaged locations. Experimental tests demonstrated that the time- and temperature-dependent strain-ageing phenomenon causes changes in the mechanical properties of plastically deformed steels. In particular, yield strength and hardness increases, whereas ductility decreases. The changes in mechanical properties are quantified and their implications on the hardness method are highlighted. Low-cycle fatigue (LCF) failures of steel reinforcing bars have been observed in laboratory testing and post-earthquake damage inspections. Often, failure might not occur during a first seismic event. However, damage is accumulated and the remaining fatigue life is reduced. Failure might therefore occur in a subsequent seismic event. Although numerous studies exist on the LCF behaviour of steel rebars, no studies had been conducted on the strain-ageing effects on the remaining fatigue life. In this thesis, the reduction in fatigue life due to this phenomenon is determined through a number of experimental tests.
Principal contractors can achieve better financial performance in civil construction projects by increasing the proportion of works delivered by subcontractors. However, anecdotally the use of subcontractors is thought to be make principal contractors less competitive due to compounding profit margins. This study found that projects with a higher proportion of subcontracted work exhibit better financial results than projects with less work delivered by subcontractors. This study uses the Christchurch Infrastructure Alliance (known as the Stronger Christchurch Infrastructure Rebuild Team, SCIRT) as a case study to observe why principal contracting firms engage subcontractors and the effect subcontracting has on the overall performance of a construction project. Five top tier civil contracting firms (known as ‘delivery teams’) participated in the alliance. Each team was responsible for the delivery of individual projects. A sample of 334 individual SCIRT projects were analysed, and key delivery team staff were surveyed, to investigate the effect subcontractor engagement has on performance. Between the five delivery teams there were clear differences in how much work was delivered via subcontracts. The extent of this subcontractor engagement had a significant effect on the relative performance of the principal contractor. A positive correlation between subcontractor engagement and overall financial performance is observed, and a negative correlation is observed between subcontractor engagement and non-financial performance. Although the causes of these relationships appear complex, the primary reason appears to be that subcontracting fosters increased productivity by cascading financial performance incentives closer to the physical construction task. To maximise competitiveness and financial performance, principal contractors must embrace the use of subcontractors and develop efficient systems of managing subcontracted work.
Objective: The nature of disaster research makes it difficult to adequately measure the impact that significant events have on a population. Large, representative samples are required, ideally with comparable data collected before the event. When Christchurch, New Zealand, was struck by multiple, devastating earthquakes, there presented an opportunity to investigate the effects of dose-related quakes (none, one, two or three over a 9-month period) on the cognition of Canterbury’s elderly population through the New Zealand Brain Research Institute’s (NZBRI’s) cognitive screening study. The related effects of having a concomitant medical condition, sex, age and estimated- full scale IQ (Est-FSIQ) on cognition were also investigated. Method: 609 participants were tested on various neuropsychological tests and a self-rated dementia scale in a one hour interview at the NZBRI. Four groups were established, based on the number of major earthquakes experienced at the time of testing: “EQ-dose: None” (N = 51) had experienced no quakes; “EQ-dose: One” (N = 193) had experienced the initial quake in September 2010; “EQ-dose: Two” (N = 82) also experienced the most devastating February 2011 quake; and “EQ-dose: Three” (N = 265) also the June 2011 quake at testing. Results: Two neuropsychological variables of Trail A and the AD8 were impacted by an EQ-dose effect, while having a medical condition was associated with poorer function on the MoCA, Rey Copy and Recall, Trail A, and AD8. Having a major medical condition led to worse performance on the Rey Copy and Recall following the major February earthquake. Males performed significantly better on Trail A and Rey Planning, while females better on the MoCA. Older participants (>73) had significantly lower scores on the MoCA than younger participants (<74), while those with a higher Est-FSIQ (>111) had better scores on the MoCA and Rey Recall than participants with a lower Est-FSIQ. Finally, predicted variable analysis (based on calculated, sample-specific Z-scores) failed to find a significant earthquake effect when variables of age, sex and Est-FSIQ were controlled for, while there was a significant effect of medical condition on each measure. Conclusion: The current thesis provides evidence suggesting resilience amongst Canterbury’s elderly population in the face of the sequence of significant quakes that struck the region over a year from September 2010. By contrast, having a major medical condition was a ‘more significant life event’ in terms of impact on cognition in this group.
Courage has remained an elusive concept to define despite having been in the English lexicon for hundreds of years. The Canterbury earthquake sequence that began in 2010 provided a unique context in which to undertake research that would contribute to further conceptualisation of courage. This qualitative study was undertaken in Christchurch, New Zealand, with adults over the age of 70 who experienced the Canterbury earthquakes and continued to live in the Canterbury region. The population group was chosen because it is an under researched group in post-disaster environments, and one that offers valuable insights because of members' length and breadth of life experiences, and likely reminiscent and reflective life stage. A constructivist grounded theory approach was utilised, with data collected through semi-structured focus groups and individual key informant interviews. The common adverse experience of the participants initially discussed was the earthquakes, which was followed by exploration of courage in their other lived experiences. Through an inductive process of data analysis, conceptual categories were identified, which when further analysed and integrated, contributed to a definition of courage. The definition was subsequently discussed with social work professionals who had remained working in the Canterbury region after experiencing the earthquakes. From the examples and the actions described within these, a process model was developed to support the application of courage. The model includes five steps: recognising an adverse situation, making a conscious decision to act, accessing sources of motivation, mastering emotion and taking action. Defining and utilising courage can help people to face adversity associated with everyday life and ultimately supports self-actualisation and self-development. Recommendations from the study include teaching about courage within social work education, utilising the process model within supervision, intentionally involving older adults in emergency management planning and developing specific social work tasks in hospital settings following a disaster.
During many years the analysis of some geophysical results of Charles Darwin was being carried out in Department. Darwin has connected almost 200 years ago results of catastrophic earthquakes with vertical movement of a surface of the Earth. Usually this movement less horizontal movement and its influence on destruction of cities is not considered. Earthquake hazard assessment studies were focused usually on the horizontal ground motion. Effects of the strong vertical motion were not, practically, discussed. The margins of safety against gravity-induced static vertical forces in constructed buildings usually provide adequate resistance to dynamic forces induced by the vertical acceleration during an earthquake. However, the earthquake in Christchurch is an example of the vertical seismic shock . The earthquake magnitude was rather small - nearby 6.3. However, the result was catastrophic. The same took place in 1835. It allowed to Darwin to formulate a few great ideas. Charles Darwin has explained qualitatively results of an interaction of huge seismic waves with volcanoes and the nature of volcanism and seismicity of our planet. These important data of Charles Darwin became very actual recently. It is possible to tell also the same about tsunami and extreme ocean waves described by Charles Darwin. Therefore this data were analyzed using modern mechanics, mathematics and physics in Department. In particular, the theory of catastrophic waves was developed based on Darwin's data. The theory tried to explain occurrence, evolution and distribution the catastrophic waves in various natural systems, since atoms, oceans, surfaces of the Earth and up to the very early Universe. Some results of the research were published in prestigious magazines. Later they were presented in two books devoted to Charles Darwin's anniversary (2009). Last from them was published in Russian (2011). We give here key ideas of this research which is a part of interdisciplinary researches of Department. Some ideas are discussed. Not less important purpose is very short historical review of some researches of Darwin. In particular, we underline Darwin' priority in the formulation of the bases of Dynamics Earth.
© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. Prediction of building collapse due to significant seismic motion is a principle objective of earthquake engineers, particularly after a major seismic event when the structure is damaged and decisions may need to be made rapidly concerning the safe occupation of a building or surrounding areas. Traditional model-based pushover analyses are effective, but only if the structural properties are well understood, which is not the case after an event when that information is most useful. This paper combines hysteresis loop analysis (HLA) structural health monitoring (SHM) and incremental dynamic analysis (IDA) methods to identify and then analyse collapse capacity and the probability of collapse for a specific structure, at any time, a range of earthquake excitations to ensure robustness. This nonlinear dynamic analysis enables constant updating of building performance predictions following a given and subsequent earthquake events, which can result in difficult to identify deterioration of structural components and their resulting capacity, all of which is far more difficult using static pushover analysis. The combined methods and analysis provide near real-time updating of the collapse fragility curves as events progress, thus quantifying the change of collapse probability or seismic induced losses very soon after an earthquake for decision-making. Thus, this combination of methods enables a novel, higher-resolution analysis of risk that was not previously available. The methods are not computationally expensive and there is no requirement for a validated numerical model, thus providing a relatively simpler means of assessing collapse probability immediately post-event when such speed can provide better information for critical decision-making. Finally, the results also show a clear need to extend the area of SHM toward creating improved predictive models for analysis of subsequent events, where the Christchurch series of 2010–2011 had significant post-event aftershocks.
This paper investigates the effects of variability in source rupture parameters on site-specific physics-based simulated ground motions, ascertained through the systematic analysis of ground motion intensity measures. As a preliminary study, we consider simulations of the 22 February 2011 Christchurch earthquake using the Graves and Pitarka (2015) methodology. The effects of source variability are considered via a sensitivity study in which parameters (hypocentre location, earthquake magnitude, average rupture velocity, fault geometry and the Brune stress parameter) are individually varied by one standard deviation. The sensitivity of simulated ground motion intensity measures are subsequently compared against observational data. The preliminary results from this study indicate that uncertainty in the stress parameter and the rupture velocity have the most significant effect on the high frequency amplitudes. Conversely, magnitude uncertainty was found to be most influential on the spectral acceleration amplitudes at low frequencies. Further work is required to extend this preliminary study to exhaustively consider more events and to include parameter covariance. The ultimate results of this research will assist in the validation of the overall simulation method’s accuracy in capturing various rupture parameters, which is essential for the use of simulated ground motion models in probabilistic seismic hazard analysis.
<b>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.</b>
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.
Millions of urban residents around the world in the coming century will experience severe landscape change – including increased frequencies of flooding due to intensifying storm events and impacts from sea level rise. For cities, collisions of environmental change with mismatched cultural systems present a major threat to infrastructure systems that support urban living. Landscape architects who address these issues express a need to realign infrastructure with underlying natural systems, criticizing the lack of social and environmental considerations in engineering works. Our ability to manage both society and the landscapes we live in to better adapt to unpredictable events and landscape changes is essential if we are to sustain the health and safety of our families, neighbourhoods, and wider community networks. When extreme events like earthquakes or flooding occur in developed areas, the feasibility of returning the land to pre-disturbance use can be questioned. In Christchurch for example, a large expanse of land (630 hectares) within the city was severely damaged by the earthquakes and judged too impractical to repair in the short term. The central government now owns the land and is currently in the process of demolishing the mostly residential houses that formed the predominant land use. Furthermore, cascading impacts from the earthquakes have resulted in a general land subsidence of .5m over much of eastern Christchurch, causing disruptive and damaging flooding. Yet, although disasters can cause severe social and environmental distress, they also hold great potential as a catalyst to increasing adaption. But how might landscape architecture be better positioned to respond to the potential for transformation after disaster? This research asks two core questions: what roles can the discipline of landscape architecture play in improving the resilience of communities so they become more able to adapt to change? And what imaginative concepts could be designed for alternative forms of residential development that better empower residents to understand and adapt the infrastructure that supports them? Through design-directed inquiry, the research found landscape architecture theory to be well positioned to contribute to goals of social-ecological systems resilience. The discipline of landscape architecture could become influential in resilience-oriented multi disciplinary collaborations, with our particular strengths lying in six key areas: the integration of ecological and social processes, improving social capital, engaging with temporality, design-led innovation potential, increasing diversity and our ability to work across multiple scales. Furthermore, several innovative ideas were developed, through a site-based design exploration located within the residential red zone, that attempt to challenge conventional modes of urban living – concepts such as time-based land use, understanding roads as urban waterways, and landscape design and management strategies that increase community participation and awareness of the temporality in landscapes.
Background: We are in a period of history where natural disasters are increasing in both frequency and severity. They are having widespread impacts on communities, especially on vulnerable communities, those most affected who have the least ability to prepare or respond to a disaster. The ability to assemble and effectively manage Interagency Emergency Response Teams (IERTs) is critical to navigating the complexity and chaos found immediately following disasters. These teams play a crucial role in the multi-sectoral, multi-agency, multi-disciplinary, and inter-organisational response and are vital to ensuring the safety and well-being of vulnerable populations such as the young, aged, and socially and medically disadvantaged in disasters. Communication is key to the smooth operation of these teams. Most studies of the communication in IERTs during a disaster have been focussed at a macro-level of examining larger scale patterns and trends within organisations. Rarely found are micro-level analyses of interpersonal communication at the critical interfaces between collaborating agencies. This study set out to understand the experiences of those working at the interagency interfaces in an IERT set up by the Canterbury District Health Board to respond to the needs of the vulnerable people in the aftermath of the destructive earthquakes that hit Canterbury, New Zealand, in 2010-11. The aim of the study was to gain insights about the complexities of interpersonal communication (micro-level) involved in interagency response coordination and to generate an improved understanding into what stabilises the interagency communication interfaces between those agencies responding to a major disaster. Methods: A qualitative case study research design was employed to investigate how interagency communication interfaces were stabilised at the micro-level (“the case”) in the aftermath of the destructive earthquakes that hit Canterbury in 2010-11 (“the context”). Participant recruitment was undertaken by mapping which agencies were involved within the IERT and approaching representatives from each of these agencies. Data was collected via individual interviews using a semi-structured interview guide and was based on the “Critical Incident Technique”. Subsequently, data was transcribed verbatim and subjected to inductive analysis. This was underpinned theoretically by Weick’s “Interpretive Approach” and supported by Nvivo qualitative data analysis software. Results: 19 participants were interviewed in this study. Out of the inductive analysis emerged two primary themes, each with several sub-factors. The first major theme was destabilising/disruptive factors of interagency communication with five sub-factors, a) conflicting role mandates, b) rigid command structures, c) disruption of established communication structures, d) lack of shared language and understanding, and e) situational awareness disruption. The second major theme stabilising/steadying factors in interagency communication had four sub-factors, a) the establishment of the IERT, b) emergent novel communication strategies, c) establishment of a liaison role and d) pre-existing networks and relationships. Finally, there was a third sub-level identified during inductive analysis, where sub-factors from both primary themes were noted to be uniquely interconnected by emergent “consequences” arising out of the disaster context. Finally, findings were synthesised into a conceptual “Model of Interagency Communication at the Micro-level” based on this case study of the Canterbury earthquake disaster response. Discussion: The three key dimensions of The People, The Connections and The Improvisations served as a framework for the discussion of what stabilises interagency communication interfaces in a major disaster. The People were key to stabilising the interagency interfaces through functioning as a flexible conduit, guiding and navigating communication at the interagency interfaces and improving situational awareness. The Connections provided the collective competence, shared decision-making and prior established relationships that stabilised the micro-level communication at interagency interfaces. And finally, The Improvisations i.e., novel ideas and inventiveness that emerge out of rapidly changing post-disaster environments, also contributed to stabilisation of micro-level communication flows across interagency interfaces in the disaster response. “Command and control” hierarchical structures do provide clear processes and structures for teams working in disasters to follow. However, improvisations and novel solutions are also needed and often emerge from first responders (who are best placed to assess the evolving needs in a disaster where there is a high degree of uncertainty). Conclusion: This study highlights the value of incorporating an interface perspective into any study that seeks to understand the processes of IERTs during disaster responses. It also strengthens the requirement for disaster management frameworks to formally plan for and to allow for the adaptive responsiveness of local teams on the ground, and legitimise and recognise the improvisations of those in the role of emergent boundary spanners in a disaster response. This needs to be in addition to existing formal disaster response mechanisms. This study provides a new conceptual model that can be used to guide future case studies exploring stability at the interfaces of other IERTs and highlights the centrality of communication in the experiences of members of teams in the aftermath of a disaster. Utilising these new perspectives on stabilising communication at the interagency interfaces in disaster responses will have practical implications in the future to better serve the needs of vulnerable people who are at greatest risk of adverse outcomes in a disaster.
Predictive modelling provides an efficient means to analyse the coastal environment and generate knowledge for long term urban planning. In this study, the numerical models SWAN and XBeach were incorporated into the ESRI ArcGIS interface by means of the BeachMMtool. This was applied to the Greater Christchurch coastal environment to simulate geomorphological evolution through hydrodynamic forcing. Simulations were performed using the recent sea level rise predictions by the Intergovernmental Panel on Climate Change (2013) to determine whether the statutory requirements outlined in the New Zealand Coastal Policy Statement 2010 are consistent with central, regional and district designations. Our results indicate that current land use zoning in Greater Christchurch is not consistent with these predictions. This is because coastal hazard risk has not been thoroughly quantified during the process of installing the Canterbury Earthquake Recovery Authority residential red zone. However, the Christchurch City Council’s flood management area does provide an extent to which managed coastal retreat is a real option. The results of this research suggest that progradation will continue to occur along the Christchurch foreshore due to the net sediment flux retaining an onshore direction and the current hydrodynamic activity not being strong enough to move sediment offshore. However, inundation during periods of storm surge poses a risk to human habitation on low lying areas around the Avon-Heathcote Estuary and the Brooklands lagoon.
Home address-based school zoning regulations are widely used in many countries as one means of selecting pupils and estimating future enrolment. However, there is little research regarding an alternative system of zoning for parents’ place of employment. Previous research has failed to analyse potential impacts from workplace-based zoning, including negating the effects of chain migration theory and settlement patterns to facilitate cultural integration, promoting the physical and mental wellbeing of families by enabling their close proximity during the day, as well as positive results concerning a volatile real estate market. As the modern family more often consists of one or both parents working full-time, the requirement of children to attend school near their home may not be as reasonably convenient as near their parents’ workplace. A case study was performed on one primary school in Christchurch, consisting of surveys and interviews of school stakeholders, including parents and staff, along with GIS mapping of school locations. This found deeper motivations for choosing a primary school, including a preference for cultural integration and the desire to school children under 14 years near their parents’ place of employment in case of illness or earthquake. These data suggest that the advantages of workplace-based zoning may be worth considering, and this thesis creates a framework for the Ministry of Education to implement this initiative in a pilot programme for primary schools in Christchurch.
