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.
Timber-based hybrid structures provide a prospective solution for utilizing environmentally friendly timber material in the construction of mid-rise or high-rise structures. This study mainly focuses on structural damage evaluation for a type of timber-steel hybrid structures, which incorporate prefabricated light wood frame shear walls into steel moment-resisting frames (SMRFs). The structural damage of such a hybrid structure was evaluated through shake table tests on a four-story large-scale timber-steel hybrid structure. Four ground motion records (i.e., Wenchuan earthquake, Canterbury earthquake, El-Centro earthquake, and Kobe earthquake) were chosen for the tests, with the consideration of three different probability levels (i.e., minor, moderate and major earthquakes) for each record. During the shake table tests, the hybrid structure performed quite well with visual damage only to wood shear walls. No visual damage in SMRF and the frame-to-wall connections was observed. The correlation of visual damage to seismic intensity, modal-based damage index and inter-story drift was discussed. The reported work provided a basis of knowledge for performance-based seismic design (PBSD) for such timber-based hybrid structures.
Post-tensioned timber technology was originally developed and researched at the University of Canterbury (UC) in New Zealand in 2005. It can provide a low-damage seismic design solution for multi-storey mass timber buildings. Since mass timber products, such as cross-laminated timber (CLT), have high in-plane stiffness, a post-tensioned timber shear wall will deform mainly in a rocking mechanism. The moment capacity of the wall at the base is commonly determined using the elastic form of the Modified Monolithic Beam Analogy (MMBA). In the calculation of the moment capacity at the wall base, it is critical to accurately predict the location of the neutral axis and the timber compressive stress distribution. Three 2/3 scale 8.6m tall post-tensioned CLT walls were experimentally tested under quasi-static cyclic loading – both uni-directional and bi-directional- in this study. These specimens included a single wall, a coupled wall, and a C-shaped core-wall. The main objective was to develop post-tensioned C-shaped timber core-walls for tall timber buildings with enhanced lateral strength and stiffness. To better understand the timber compressive stress distributions at the wall base, particle tracking technology (PTT) technology was applied for the first time to investigate the behaviour of the compression toe. Previous post-tensioned timber testing primarily used the displacement measurements to determine the timber compressive behavior at the wall base or rocking interfaces. However, by using PTT technology, the timber strain measurements in the compression zone can be much more accurate as PTT is able to track the movement of many particles on the timber surface. This paper presents experimental testing results of post-tensioned CLT walls with a focus on capturing timber compressive behavior using PTT. The PTT measurements were able to better capture small base rotations which occurred at the onset of gap opening and capture unexpected phenomena in core-wall tests. The single wall test result herein presented indicates that while the MMBA could predict the moment rotation behavior with reasonable accuracy, the peak strain response was under predicted in the compression toe. Further detailed study is required to better understand the complex strain fields generated reflective of the inherent cross-thickness inhomogeneity and material variability of CLT.
This study analyses the Earthquake Commission’s (EQC) insurance claims database to investigate the influence of seismic intensity and property damage resulting from the Canterbury Earthquake Sequence (CES) on the repair costs and claim settlement duration for residential buildings. Firstly, the ratio of building repair cost to its replacement cost was expressed as a Building Loss Ratio (BLR), which was further extended to Regional Loss Ratio (RLR) for greater Christchurch by multiplying the average of all building loss ratios with the proportion of building stock that lodged an insurance claim. Secondly, the total time required to settle the claim and the time taken to complete each phase of the claim settlement process were obtained. Based on the database, the regional loss ratio for greater Christchurch for three events producing shakings of intensities 6, 7, and 8 on the modified Mercalli intensity scale were 0.013, 0.066, and 0.171, respectively. Furthermore, small (less than NZD15,000), medium (between NZD15,000 and NZD100,000), and large (more than NZD100,000) claims took 0.35-0.55, 1.95-2.45, and 3.35-3.85 years to settle regardless of the building’s construction period and earthquake intensities. The number of claims was also disaggregated by various building characteristics to evaluate their relative contribution to the damage and repair costs.
Pumice materials, which are problematic from an engineering viewpoint, are widespread in the central part of the North Island. Considering the impacts of the 2010-2011 Christchurch earthquakes, a clear understanding of their properties under earthquake loading is necessary. For example, the 1987 Edgecumbe earthquake showed evidence of localised liquefaction of sands of volcanic origin. To elucidate on this, research was undertaken to investigate whether existing empirical field-based methods to evaluate the liquefaction potential of sands, which were originally developed for hard-grained soils, are applicable to crushable pumice-rich deposits. For this purpose, two sites, one in Whakatane and another in Edgecumbe, were selected where the occurrence of liquefaction was reported following the Edgecumbe earthquake. Manifestations of soil liquefaction, such as sand boils and ejected materials, have been reported at both sites. Field tests, including cone penetration tests (CPT), shear-wave velocity profiling, and screw driving sounding (SDS) tests were performed at the sites. Then, considering estimated peak ground accelerations (PGAs) at the sites based on recorded motions and possible range of ground water table locations, liquefaction analysis was conducted at the sites using available empirical approaches. To clarify the results of the analysis, undisturbed soil samples were obtained at both sites to investigate the laboratory-derived cyclic resistance ratios and to compare with the field-estimated values. Research results clearly showed that these pumice-rich soils do not fit existing liquefaction assessment frameworks and alternate methods are necessary to characterise them.
Low Damage Seismic Design (LDSD) guidance material being developed by Engineering NZ is considering a design drift limit for multi-storey buildings of 0.5% at a new damage control limit state (DCLS). The impact of this new design requirement on the expected annual loss due to repair costs is investigated for a four-storey office building with reinforced concrete walls located in Christchurch. The LDSD guidance material aims to reduce the expected annual loss of complying buildings to below 0.1% of building replacement cost. The research tested this expectation. Losses were estimated in accordance with FEMA P58, using building responses from non-linear time history analyses (performed with OpenSees using lumped plasticity models). The equivalent static method, in line with NZS 1170.5 and NZS 3101, was used to design the building to LDSD specifications, representing a future state-of-practice design. The building designed to low-damage specification returned an expected annual loss of 0.10%, and the building designed conventionally returned an expected annual loss of 0.13%. Limitations with the NZS 3101 method for determining wall stiffness were identified, and a different method acknowledging the relationship between strength and stiffness was used to redesign the building. Along with improving this design assumption, the study finds that LDSD design criteria could be an effective way of limiting damage and losses.
Field surveys and experimental studies have shown that light steel or timber framed plasterboard partition walls are particularly vulnerable to earthquake damage prompting the overarching objective of this research, which is to further the development of low damage seismic systems for non-structural partition walls in order to facilitate their adoption by industry to assist with reducing the losses associated with the maintenance and repair cost of buildings across their design life. In particular, this study focused on the behaviour of steel-framed partition walls systems with novel detailing that aim to be “low-damage” designed according to common practice for walls used in commercial and institutional buildings in New Zealand. This objective was investigated by (1) investigating the performance of a flexible track system proposed by researchers and industry by experimental testing of full-scale specimens; (2) investigating the performance of the seismic gap partition wall systems proposed in a number of studies, further developed in this study with input from industry, by experimental testing of full-scale specimens; and (3) investigating the potential implications of using these systems compared with traditionally detailed partition wall systems within multi-storey buildings using the Performance Based Earthquake Engineering loss assessment methodology. Three full-scale testing frames were designed in order to replicate, under controlled laboratory conditions, the effects of seismic shaking on partition walls within multi-storey buildings by the application of quasi-static uni-directional cyclic loading imposing an inter-storey drift. The typical configuration for test specimens was selected to be a unique “y-shape”, including one angled return wall, with typical dimensions of approximately 2400 mm along the main wall and 600 mm along (approximately) the returns walls with a height of 2405 mm from floor to ceiling. The specimens were aligned within test frames at an oblique angle to the direction of loading in order to investigate bi- directional effects. Three wall specimens with flexible track detailing, two identical plane specimens and the third including a doorway, were tested. The detailing involved removing top track anchors within the proximity of wall intersections, thus allowing the tracks to ‘bow’ out at these locations. Although the top track anchors were specified to be removed the proximity of wall intersections, a construction error was made whereby a single top track slab to concrete anchor was left in at the three-way wall junction. Despite this error, the experimental testing was deemed worthwhile since such errors will also occur in practice and because the behaviour of the wall can be examined with this fixing in mind. The specimens also included an acoustic/fire sealant at the top lining to floor boundary. In addition to providing drift capacities, the force-displacement behaviour is also reported, the dissipated energy was computed, and the parameters of the Wayne-Stewart hysteretic model were fitted to the results. The specimen with the door opening behaved significantly different to the plane specimens: damage to the doorway specimen began as cracking of the wallboard propagating from the corners of the doorway following which the L- and Y- shaped junctions behaved independently, whereas damage to the plane specimens began as cracking of the wallboard at the top of the L-junction and wall system deformed as a single unit. The results suggest that bi-directional behaviour is important even if its impact cannot be directly quantified by the experiments conducted. Damage to sealant implies that the bond between plasterboard and sealant is important for its seismic performance. Careful quality control is advised as defects in the bond may significantly impact its ability to withstand seismic movement. Two specimens with seismic gap detailing were tested: a steel stud specimen and a timber stud specimen. Observed drift capacities were significantly greater than traditional plasterboard partition systems. Equations were used to predict the drift at which damage state 1 (DS1) and damage state 2 (DS2) would initiate. The equation used to estimate the drift at the onset of DS1 accurately predicted the onset of plaster cracking but overestimated the drift at which the gap filling material was damaged. The equation used to predict the onset of DS2 provided a lower bound for both specimens and also when used to predict results of previous experimental tests on seismic gap systems. The gap-filling material reduced the drift at the onset of DS1, however, it had a beneficial effect on the re-centring behaviour of the linings. Out-of-plane displacements and return wall configuration did not appear to significantly impact the onset of plaster cracking in the specimens. A loss assessment according to the PBEE methodology was conducted on four steel MRF case study buildings: (1) a 4-storey building designed for the Christchurch region, (2) a 4-storey building designed for the Wellington region, (3) a 12-storey building designed for the Christchurch region, and (4) a 12- storey building designed for the Wellington region. The fragility parameters for a traditional partition system, the flexible track partition system, and the seismic gap steel stud and timber stud partition systems were included within the loss assessment. The order (lowest to highest) of each system in terms of the expected annual losses of each building when incorporating the system was, (1) the seismic gap timber stud system, (2) the seismic gap steel stud system, (3) the traditional/baseline system, and (4) the flexible track system. For the seismic gap timber stud system, which incurred the greatest reduction in expected annual losses for each case study building, the reduction in expected annual losses in comparison to the losses found when using the traditional system ranged from a 5% to a 30% reduction. This reinforces the fact that while there is a benefit to the using low damage partition systems in each building the extent of reduction in expected annual losses is significantly dependent on the particular building design and its location. The flexible track specimens had larger repair costs at small hazard levels compared to the traditional system but smaller repair costs at larger hazard levels. However, the resulting expected annual losses for the flexible track system was higher than the traditional system which reinforces findings from past studies which observed that the greatest contribution to expected annual losses arises from low to moderate intensity shaking seismic events (low hazard levels).
This chapter will draw on recent literature and practice experience to discuss the nature of field education in Aotearoa New Zealand. Social work education in this country is provided by academic institutions that are approved by the Social Workers Registration Board. The field education curriculum is therefore shaped by both the regulatory body and the tertiary institutions. Significant numbers of students undertake field education annually which places pressure on industry and raises concerns as to the quality of student experience. Although the importance of field education is undisputed it remains poised in a liminal space between the tertiary education and social service sectors where it is not sufficiently resourced by either. This affects the provision of practice placements as well as the establishment of long-term cross-sector partnerships. Significant events such as the 2010 and 2011 Christchurch earthquakes and recent terrorist attacks have exposed students to different field education experiences signalling the need for programmes to be responsive. Examples of creative learning opportunities in diverse environments, including in indigenous contexts, will be described. Drawing upon recent research, we comment on student and field educator experiences of supervision in the field. Recommendations to further develop social work field education in Aotearoa New Zealand relate to resourcing, infrastructure and quality, support for field educators, and assessment.
To reduce seismic vulnerability and the economic impact of seismic structural damage, it is important to protect structures using supplemental energy dissipation devices. Several types of supplemental damping systems can limit loads transferred to structures and absorb significant response energy without sacrificial structural damage. Lead extrusion dampers are one type of supplemental energy dissipation devices. A smaller volumetric size with high force capacities, called high force to volume (HF2V) devices, have been employed in a large series of scaled and full-scaled experiments, as well as in three new structures in Christchurch and San Francisco. HF2V devices have previously been designed using very simple models with limited precision. They are then manufactured, and tested to ensure force capacities match design goals, potentially necessitating reassembly or redesign if there is large error. In particular, devices with a force capacity well above or below a design range can require more testing and redesign, leading to increased economic and time cost. Thus, there is a major need for a modelling methodology to accurately estimate the range of possible device force capacity values in the design phase – upper and lower bounds. Upper and lower bound force capacity estimates are developed from equations in the metal extrusion literature. These equations consider both friction and extrusion forces between the lead and the bulged shaft in HF2V devices. The equations for the lower and upper bounds are strictly functions of device design parameters ensuring easy use in the design phase. Two different sets of estimates are created, leading to estimates for the lower and upper bounds denoted FLB,1, FUB,1, FUB,2, respectively. The models are validated by comparing the bounds with experimental force capacity data from 15 experimental HF2V device tests. All lower bound estimates are below or almost equal to the experimental device forces, and all upper bound estimates are above. Per the derivation, the (FLB,1, FUB,1) pair provide narrower bounds. The (FLB,1, FUB,1) pair also had a mean lower bound gap of -34%, meaning the lower bound was 74% of device force on average, while the mean upper bound gap for FUB,1 was +23%. These are relatively tight bounds, within ~±2 SE of device manufacture, and can be used as a guide to ensure device forces are in range for the actual design use when manufactured. Therefore, they provide a useful design tool.
Nel presente articolo si illustra una procedura per il processamento automatizzato di prove CPT, il calcolo di vari indici di liquefazione e la rappresentazione dei dati su mappa. La procedura è applicata al caso studio del terremoto di Christchurch, Nuova Zelanda, del 22 febbraio 2011 (magnitudo momento, Mw = 6.2). Dall’analisi spaziale dei risultati emerge una buona correlazione tra le mappe ottenute per l’indicatore degli effetti al suolo e i danni osservati (su terreni e strutture). Tuttavia, per confermare la validità di tale procedura, sarà necessario esaminare ulteriori casi studio nel mondo.
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.
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This thesis addresses the topic of local bond behaviour in RC structures. The mechanism of bond refers to the composite action between deformed steel reinforcing bars and the surrounding concrete. Bond behaviour is an open research topic with a wide scope, particularly because bond it is such a fundamental concept to structural engineers. However, despite many bond-related research findings having wide applications, the primary contribution of this research is an experimental evaluation of the prominent features of local bond behaviour and the associated implications for the seismic performance of RC structures. The findings presented in this thesis attempt to address some structural engineering recommendations made by the Canterbury Earthquakes Royal Commission following the 2010-2011 Canterbury (New Zealand) earthquake sequence. A chapter of this thesis discusses the structural behaviour of flexure-dominated RC wall structures with an insufficient quantity of longitudinal reinforcement, among other in situ conditions, that causes material damage to predominantly occur at a single crack plane. In this particular case, the extent of concrete damage and bond deterioration adjacent to the crack plane will influence the ductility capacity that is effectively provided by the reinforcing steel. As a consequence of these in situ conditions, some lightly reinforced wall buildings in Christchurch lost their structural integrity due to brittle fracture of the longitudinal reinforcement. With these concerning post-earthquake observations in mind, there is the underlying intention that this thesis presents experimental evidence of bond behaviour that allows structural engineers to re-assess their confidence levels for the ability of lightly reinforced concrete structures to achieve the life-safety seismic performance objective the ultimate limit state. Three chapters of this thesis are devoted to the experimental work that was conducted as the main contribution of this research. Critical details of the experimental design, bond testing method and test programme are reported. The bond stress-slip relationship was studied through 75 bond pull-out tests. In order to measure the maximum local bond strength, all bond tests were carried out on deformed reinforcing bars that did not yield as the embedded bond length was relatively short. Bond test results have been presented in two separate chapters in which 48 monotonic bond tests and 27 cyclic bond tests are presented. Permutations of the experiments include the loading rate, cyclic loading history, concrete strength (25 to 70 MPa), concrete age, cover thickness, bar diameter (16 and 20 mm), embedded length, and position of the embedded bond region within the specimen (close or far away to the free surface). The parametric study showed that the concrete strength significantly influences the maximum bond strength and that it is reasonable to normalise the bond stress by the square-root of the concrete compressive strength, √(f'c). The generalised monotonic bond behaviour is described within. An important outcome of the research is that the measured bond strength and stiffness was higher than stated by the bond stress-slip relationship in the fib Model Code 2010. To account for these observed differences, an alternative model is proposed for the local monotonic bond stress-slip relationship. Cyclic bond tests showed a significant proportion of the total bond degradation occurs after the loading cycle in the peak bond strength range, which is when bond slip has exceeded 0.5 mm. Subsequent loading to constant slip values showed a linear relationship between the amount of bond strength degradation and the log of the number of cycles that were applied. To a greater extent, the cyclic bond deterioration depends on the bond slip range, regardless of whether the applied load cycling is half- or fully-reversed. The observed bond deterioration and hysteretic energy dissipated during cyclic loading was found to agree reasonably well between these cyclic tests with different loading protocols. The cyclic bond deterioration was also found to be reasonably consistent exponential damage models found in the literature. This research concluded that the deformed reinforcing bars used in NZ construction, embedded in moderate to high strength concrete, are able to develop high local bond stresses that are mobilised by a small amount of local bond slip. Although the relative rib geometry was not varied within this experimental programme, a general conclusion of this thesis is that deformed bars currently available in NZ have a relative rib bearing area that is comparatively higher than the test bars used in previous international research. From the parametric study it was found that the maximum monotonic bond strength is significant enhanced by dynamic loading rates. Experimental evidence of high bond strength and initial bond stiffness generally suggests that only a small amount of local bond slip that can occur when the deformed test bar was subjected to large tension forces. Minimal bond slip and bond damage limits the effective yielding length that is available for the reinforcing steel to distribute inelastic material strains. Consequently, the potential for brittle fracture of the reinforcement may be a more problematic and widespread issue than is apparent to structural engineers. This research has provided information that improve the reliability of engineering predictions (with respect to ductility capacity) of maximum crack widths and the extent of bond deterioration that might occur in RC structures during seismic actions.
With origins in the South Bronx area of New York in the early 1970s, hip-hop culture is now produced and consumed globally. While hip-hop activities can be varied, hip-hop is generally considered to have four forms or “elements”: DJing, MCing, b-boying/b-girling, and graffiti. Although all four elements of hip-hop have become a part of many youth work initiatives across the globe, public debate and controversy continue to surround hip-hop activities. Very little research and literature has explored the complexities involved in the assembling of hip-hop activities in youth work sites of practice using these hip-hop elements. This study attends to the gap in hip-hop and human service literature by tracing how hip-hop activities were assembled in several sites of youth work activity in Christchurch, New Zealand. Actor-network theory (ANT) is the methodological framework used to map the assemblage of hip-hop-youth work activities in this study. ANT follows how action is distributed across both human and non-human actors. By recognising the potential agency of “things”, this research traces the roles played by human actors, such as young people and youth workers, together with those of non-human actors such as funding documents, social media, clothing, and youth venue equipment. This ethnographic study provides rich descriptions or “snapshots” of some of the key socio-material practices that shaped the enactment of hip-hop-youth work activities. These are derived from fieldwork undertaken between October 2009 and December 2011, where participant observation took place across a range of sites of hip-hop-youth work activity. In addition to this fieldwork, formal interviews were undertaken with 22 participants, the majority being youth workers, young people, and youth trust administrators. The ANT framework reveals the complexity of the task of assembling hip-hop in youth work worlds. The thesis traces the work undertaken by both human and non-human actors in generating youth engagement in hip-hop-youth work activities. Young people’s hip-hop interests are shown to be varied, multiple, and continually evolving. It is also shown how generating youth interest in hip-hop-youth work activities involved overcoming young people’s indifference or lack of awareness of the hip-hop resources a youth trust had on offer. Furthermore, the study highlights where hip-hop activities were edited or “tinkered” with to avoid hip-hop “bads”. The thesis also unpacks how needed resources were enlisted, and how funders’ interests were translated into supporting hip-hop groups and activities. By tracing the range of actors mobilised to enact hip-hop-youth work activities, this research reveals how some youth trusts could avoid having to rely on obtaining government funds for their hip-hop activities. The thesis also includes an examination of one youth trust’s efforts to reconfigure its hip-hop activities after the earthquakes that struck Christchurch city in 2010 and 2011. Working both in and on the world, the text that is this thesis is also understood as an intervention. This study constitutes a deliberate attempt to strengthen understandings of hip-hop as a complex, multiple, and fluid entity. It therefore challenges traditional media and literature representations that simplify and thus either stigmatise or celebrate hip-hop. As such, this study opens up possibilities to consider the opportunities, as well as the complexities of assembling hip-hop in youth work sites of practice.
The Canterbury Earthquake Sequence (CES) of 2010-2011 produced large seismic moments up to Mw 7.1. These large, near-to-surface (<15 km) ruptures triggered >6,000 rockfall boulders on the Port Hills of Christchurch, many of which impacted houses and affected the livelihoods of people within the impacted area. From these disastrous and unpredicted natural events a need arose to be able to assess the areas affected by rockfall events in the future, where it is known that a rockfall is possible from a specific source outcrop but the potential boulder runout and dynamics are not understood. The distribution of rockfall deposits is largely constrained by the physical properties and processes of the boulder and its motion such as block density, shape and size, block velocity, bounce height, impact and rebound angle, as well as the properties of the substrate. Numerical rockfall models go some way to accounting for all the complex factors in an algorithm, commonly parameterised in a user interface where site-specific effects can be calibrated. Calibration of these algorithms requires thorough field checks and often experimental practises. The purpose of this project, which began immediately following the most destructive rupture of the CES (February 22, 2011), is to collate data to characterise boulder falls, and to use this information, supplemented by a set of anthropogenic boulder fall data, to perform an in-depth calibration of the three-dimensional numerical rockfall model RAMMS::Rockfall. The thesis covers the following topics: • Use of field data to calibrate RAMMS. Boulder impact trails in the loess-colluvium soils at Rapaki Bay have been used to estimate ranges of boulder velocities and bounce heights. RAMMS results replicate field data closely; it is concluded that the model is appropriate for analysing the earthquake-triggered boulder trails at Rapaki Bay, and that it can be usefully applied to rockfall trajectory and hazard assessment at this and similar sites elsewhere. • Detailed analysis of dynamic rockfall processes, interpreted from recorded boulder rolling experiments, and compared to RAMMS simulated results at the same site. Recorded rotational and translational velocities of a particular boulder show that the boulder behaves logically and dynamically on impact with different substrate types. Simulations show that seasonal changes in soil moisture alter rockfall dynamics and runout predictions within RAMMS, and adjustments are made to the calibration to reflect this; suggesting that in hazard analysis a rockfall model should be calibrated to dry rather than wet soil conditions to anticipate the most serious outcome. • Verifying the model calibration for a separate site on the Port Hills. The results of the RAMMS simulations show the effectiveness of calibration against a real data set, as well as the effectiveness of vegetation as a rockfall barrier/retardant. The results of simulations are compared using hazard maps, where the maximum runouts match well the mapped CES fallen boulder maximum runouts. The results of the simulations in terms of frequency distribution of deposit locations on the slope are also compared with those of the CES data, using the shadow angle tool to apportion slope zones. These results also replicate real field data well. Results show that a maximum runout envelope can be mapped, as well as frequency distribution of deposited boulders for hazard (and thus risk) analysis purposes. The accuracy of the rockfall runout envelope and frequency distribution can be improved by comprehensive vegetation and substrate mapping. The topics above define the scope of the project, limiting the focus to rockfall processes on the Port Hills, and implications for model calibration for the wider scientific community. The results provide a useful rockfall analysis methodology with a defensible and replicable calibration process, that has the potential to be applied to other lithologies and substrates. Its applications include a method of analysis for the selection and positioning of rockfall countermeasure design; site safety assessment for scaling and demolition works; and risk analysis and land planning for future construction in Christchurch.
Abstract The original intention for the Partnership Community Worker (PCW) project in 2006 was for it to be an extension of the Pegasus Health General Practice and furthermore to be a bridge between the community and primary healthcare. It was believed that a close working relationship between the Practice Nurse and the PCW would help the target population of Māori, Pacifica and low income people to address and overcome their perceived barriers to healthcare which included: finance, transport, anxiety, cultural issues, communication, or lack of knowledge. Seven years later although the PCW project has been deemed a success in the Canterbury District Health Board annual reports (2013-14) and community and government agencies, including the Christchurch Resettlement Service (2012), many of the Pegasus Health General Practices have not utilised the project to its full extent, hence the need for this research. I was interested in finding out in the first instance if the model had changed and, if so why, and in the second instance if the promotional material currently distributed by Pegasus Health Primary Health Organisation reflected the daily practice of the PCW. A combination of methods were used including: surveys to the Pegasus Health General Practices, interviews with PCWs, interviews with managers of both the PCW host organisations and referring agencies to the PCW project. All the questions asked of all the participants in this research were focussed on their own perception of the role of the PCW. Results showed that the model has changed and although the publications were not reflecting the original intention of the project they did reflect the daily practice of the PCWs who are now struggling to meet much wider community expectations and needs. Key Results: Partnership Community Worker (PCW) interviews: Seventeen PCWs of the 19 employed were interviewed face to face. A number expressed interest in more culturally specific training and some are pursuing qualifications in social work; for many pay parity is an issue. In addition, many felt overwhelmed by the expectations around clients with mental health issues and housing issues now, post-earthquakes. Medical Practice surveys: Surveys were sent to eighty-two Pegasus Health medical practices and of these twenty five were completed. Results showed the full capacity of the PCW role was not clearly understood by all with many believing it was mostly a transport service. Those who did understand the full complexity of the role were very satisfied with the outcomes. PCW Host Community Manager Interviews: Of the ten out of twelve managers interviewed, some wished for more communication with Pegasus Health management because they felt aspects of both the PCW role and their own role as managers had become blurred over time. Referring organisations: Fifteen of the fifty referring community or government organisations participated. The overall satisfaction of the service was high and some acknowledged the continuing need for PCWs to be placed in communities where they were well known and trusted. Moreover results also showed that both the Canterbury earthquakes 2010-2011 and the amalgamation of Partnership Health PHO and Pegasus Health Charitable Limited in 2013 have contributed to the change of the model. Further future research may also be needed to examine the long term effects on the people of Canterbury involved in community work during the 2011-2014 years.
In the aftermath of the 2010-2011 Canterbury Earthquake Sequence (CES), the location of Christchurch-City on the coast of the Canterbury Region (New Zealand) has proven crucial in determining the types of- and chains of hazards that impact the city. Very rapidly, the land subsidence of up to 1 m (vertical), and the modifications of city’s waterways – bank sliding, longitudinal profile change, sedimentation and erosion, engineered stop-banks… - turned rainfall and high-tides into unprecedented floods, which spread across the eastern side of the city. Within this context, this contribution presents two modeling results of potential floods: (1) results of flood models and (2) the effects of further subsidence-linked flooding – indeed if another similar earthquake was to strike the city, what could be the scenarios of further subsidence and then flooding. The present research uses the pre- and post-CES LiDAR datasets, which have been used as the boundary layer for the modeling. On top of simple bathtub model of inundation, the river flood model was conducted using the 2-D hydrodynamic code NAYS-2D developed at the University of Hokkaido (Japan), using a depth-averaged resolution of the hydrodynamic equations. The results have shown that the area the most at risk of flooding are the recent Holocene sedimentary deposits, and especially the swamplands near the sea and in the proximity of waterways. As the CES drove horizontal and vertical displacement of the land-surface, the surface hydrology of the city has been deeply modified, increasing flood risks. However, it seems that scientists and managers haven’t fully learned from the CES, and no research has been looking at the potential future subsidence in further worsening subsidence-related floods. Consequently, the term “coastal quake”, coined by D. Hart is highly topical, and most especially because most of our modern cities and mega-cities are built on estuarine Holocene sediments.
We examined changes in psychological distress experienced by residents of Christchurch following two catastrophic earthquakes in late 2010 and early 2011, using data from the New Zealand Attitudes and Values Study (NZAVS), a national probability panel study of New Zealand adults. Analyses focused on the 267 participants (172 women, 95 men) who were living in central Christchurch in 2009 (i.e., before the Christchurch earthquakes), and who also provided complete responses to our yearly panel questionnaire conducted in late 2010 (largely between the two major earthquakes), late 2011, and late 2012. Levels of psychological distress were similar across the different regions of central Christchurch immediately following the September 2010 earthquake, and remained comparable across regions in 2011. By late 2012, however, average levels of psychological distress in the regions had diverged as a function of the amount of property damage experienced within each given region. Specifically, participants in the least damaged region (i.e., the Fendalton-Waimairi and Riccarton-Wigram wards) experienced greater drops in psychological distress than did those in the moderately damaged region (i.e., across the Spreydon-Heathcote and Hagley- Ferrymead wards). However, the level of psychological distress reported by participants in the most damaged region (i.e., across Shirley-Papanui and Burwood-Pegasus) were not significantly different to those in the least damaged region of central Christchurch. These findings suggest that different patterns of psychological recovery emerged across the different regions of Christchurch, with the moderately damaged region faring the worst, but only after the initial shock of the destruction had passed.
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Organisations play a vital role in assisting communities to recover from disasters. They are the key providers of goods and services needed in both response and recovery efforts. They provide the employment which both anchors people to place and supports the taxation base to allow for necessary recovery spending. Finally, organisations are an integral part of much day to day functioning contributing immensely to people’s sense of ‘normality’ and psychological wellbeing. Yet, despite their overall importance in the recovery process, there are significant gaps in our existing knowledge with regard to how organisations respond and recover following disaster. This research fills one part of this gap by examining collaboration as an adaptive strategy enacted by organisations in the Canterbury region of New Zealand, which was heavily impacted by a series of major earthquakes, occurring in 2010 and 2011. Collaboration has been extensively investigated in a variety of settings and from numerous disciplinary perspectives. However, there are few studies that investigate the role of collaborative approaches to support post-disaster business recovery. This study investigates the type of collaborations that have occurred and how they evolved as organisations reacted to the resource and environmental change caused by the disaster. Using data collected through semi-structured interviews, survey and document analysis, a rich and detailed picture of the recovery journey is created for 26 Canterbury organisations including 14 collaborators, six non-traders, five continued traders and one new business. Collaborations included two or more individual businesses collaborating along with two multi-party, place based projects. Comparative analysis of the organisations’ experiences enabled the assessment of decisions, processes and outcomes of collaboration, as well as insight into the overall process of business recovery. This research adopted a primarily inductive, qualitative approach, drawing from both grounded theory and case study methodologies in order to generate theory from this rich and contextually situated data. Important findings include the importance of creating an enabling context which allows organisations to lead their own recovery, the creation of a framework for effective post-disaster collaboration and the importance of considering both economic and other outcomes. Collaboration is found to be an effective strategy enabling resumption of trade at a time when there seemed few other options available. While solving this need, many collaborators have discovered significant and unexpected benefits not just in terms of long term strategy but also with regard to wellbeing. Economic outcomes were less clear-cut. However, with approximately 70% of the Central Business District demolished and rebuilding only gaining momentum in late 2014, many organisations are still in a transition stage moving towards a new ‘normal’.
This thesis examines how 18 University of Canterbury students based in Christchurch experienced housing insecurity during the three years after a series of major earthquakes from late 2010 and throughout 2011. I adopted a qualitative exploratory approach to gather students’ accounts and examine their experiences which were analysed using constructivist grounded theory methods. Three core categories were identified from the data: mobility, recreating security, and loss. Mobility included the effects of relocation and dislocation, as well as how the students searched for stability. Recreating security required a renewed sense of belonging and also addressed the need to feel physically safe. Lastly, loss included the loss of material possessions and also the loss of voice and political representation. The theory that emerged from these findings is that the extent to which students were able to control their mobility largely explained their experiences of housing insecurity. When students experienced a loss of control over their mobility they effectively addressed this by being resourceful and drawing on existing forms of capital. This resourcefulness generated a new form of capital, here called security capital, which represents a conceptual contribution to existing debates on students’ experiences of homelessness in a disaster context.
Canterbury, New Zealand, was struck by two major earthquakes in 2010 and 2011. Using a dyadic and developmental perspective, the current thesis first aimed to determine how the experience of earthquake-related stressors (including loss of material resources, trauma exposure, and ongoing earthquake-related stressors) and stress (posttraumatic stress symptoms) impacted individuals’ intimate relationship quality (Part 1). Data were collected from a sample of 99 couples at four time points over a period of approximately 15 months, with Time 1 completed 14 months after the 2010 earthquake (eight months post the 2011 earthquake). Data were analysed using moderated growth curve modelling in an Actor-Partner Interdependence Model framework. In line with expectations, posttraumatic stress symptoms were the strongest predictors of relationship quality. More specifically, individuals’ (actor) posttraumatic stress symptoms and their partner’s posttraumatic stress symptoms had an adverse effect on their relationship quality at Time 1. Demonstrating the importance of taking a developmental perspective, the effect of partner posttraumatic stress symptoms changed over time. Although higher partner posttraumatic stress symptoms were associated with worse relationship quality in individuals (actors) at Time 1, this was no longer the case at Time 4. Differences were also found between men and women’s actor posttraumatic stress symptom slopes across time. Using the same data and analyses, Part 2 built on these findings by investigating the role of a possible posttrauma resource available within the relationship – support exchanges. Overall, results showed that individuals were protected from any adverse effects that posttraumatic stress symptoms had on relationship quality if they had more frequent support exchanges in the relationship, however, differences between men and women and slopes across time were found. Although not the case initially, individuals’ relationship quality was worse in the longer-term if their partner reported receiving lower support from them when they were experiencing high posttraumatic stress symptoms. Results also suggested that although women coped better (as evidenced through slightly better relationship quality) with higher symptoms and lower support than men initially, these efforts diminished over time. Furthermore, men appeared to be less able to cope (i.e., had worse relationship quality) with their partner’s stress when they were not receiving frequent support. Contrary to expectations, negative exchanges in the relationship did not exacerbate any adverse effects that posttraumatic stress symptoms (experienced by either individuals or their partner) had on an individuals’ relationship quality. The theoretical and practical implications and applications of these findings are discussed.
Recurrent liquefaction in Christchurch during the 2010-2011 Canterbury earthquake sequence created a wealth of shallow subsurface intrusions with geometries and orientations governed by (1) strong ground motion severity and duration, and (2) intrinsic site characteristics including liquefaction susceptibility, lateral spreading severity, geomorphic setting, host sediment heterogeneity, and anthropogenic soil modifications. We present a suite of case studies that demonstrate how each of these characteristics influenced the geologic expressions of contemporary liquefaction in the shallow subsurface. We compare contemporary features with paleo-features to show how geologic investigations of recurrent liquefaction can provide novel insights into the shaking characteristics of modern and paleo-earthquakes, the influence of geomorphology on liquefaction vulnerability, and the possible controls of anthropogenic activity on the geologic record. We conclude that (a) sites of paleo-liquefaction in the last 1000-2000 years corresponded with most severe liquefaction during the Canterbury earthquake sequence, (b) less vulnerable sites that only liquefied in the strongest and most proximal contemporary earthquakes are unlikely to have liquefied in the last 1000-2000 years or more, (c) proximal strong earthquakes with large vertical accelerations favoured sill formation at some locations, (d) contemporary liquefaction was more severe than paleoliquefaction at all study sites, and (e) stratigraphic records of successive dike formation were more complete at sites with severe lateral spreading, (f) anthropogenic fill suppressed surface liquefaction features and altered subsurface liquefaction architecture.
This paper presents a seismic velocity model of Canterbury, New Zealand based on 3D geologic surfaces and velocities from a range of data sources. The model provides the 3D crustal structure in the region at multiple length scales for seismic wave propagation simulations, such as broadband ground motion and shallow site response analyses related to understanding the ground motions and site responses during the 2010- 2011 Canterbury earthquakes. Pre-Quaternary geologic horizons are calculated based on the reinterpretation of a comprehensive network of seismic reflection surveys from seven different campaigns over the past 50 years, as well as point constraints across an array of petroleum industry drill holes. Particular attention is given to a detailed representation of Quaternary stratigraphy, representing shallow (z<250m) near-surface layers in the model. Seismic velocities are obtained from seismic reflection processing (for Vp) and also recently performed active and passive surface wave analyses (for Vs). Over 1,700 water wells in the region are used to constrain the complex inter-bedded Quaternary stratigraphy (gravels, sands, silts, organics etc.) near the coastline, including beneath urban Christchurch, which has resulted from fluvial deposition and marine regression and transgression. For the near-surface Springston and Christchurch Formations in the Christchurch urban area (z<50m), high-spatial resolution seismic velocities (including Vs30 ) were obtained from over 13,000 cone penetration tests combined with a recently developed CPT-Vs correlation.
A major hazard accompanying earthquake shaking in areas of steep topography is the detachment of rocks from bedrock outcrops that subsequently slide, roll, or bounce downslope (i.e. rockfalls). The 2010-2011 Canterbury earthquake sequence caused recurrent and severe rockfall in parts of southern Christchurch. Coseismic rockfall caused five fatalities and significant infrastructural damage during the 2011 Mw 6.2 Christchurch earthquake. Here we examine a rockfall site in southern Christchurch in detail using geomorphic mapping, lidar analysis, geochronology (cosmogenic 3He dating, radiocarbon dating, optically stimulated luminescence (OSL) from quartz, infrared stimulated luminescence from K-feldspar), numerical modeling of rockfall boulder trajectories, and ground motion prediction equations (GMPEs). Rocks fell from the source cliff only in earthquakes with interpolated peak ground velocities exceeding ~10 cm/s; hundreds of smaller earthquakes did not produce rockfall. On the basis of empirical observations, GMPEs and age chronologies we attribute paleo-rockfalls to strong shaking in prehistoric earthquakes. We conclude that earthquake shaking of comparable intensity to the strongest contemporary earthquakes in Christchurch last occurred at this site approximately 5000 to 7000 years ago, and that in some settings, rockfall deposits provide useful proxies for past strong ground motions.
This paper summarizes the development of a high-resolution surficial shear wave velocity model based on the combination of the large high-spatial-density database of cone penetration test (CPT) logs in and around Christchurch, New Zealand and a recently-developed Christchurch-specific empirical correlation between soil shear wave velocity and CPT. This near-surface shear wave velocity model has applications for site characterization efforts via the development of maps of time-averaged shear wave velocities over specific depths, as well as use in site response analysis and ground motion simulation.
The Canterbury earthquakes have generated economic demand and supply volatility, highlighting geographical and structural interdependencies. Post-earthquake reconstruction and new developments have seen skills training, relocation, recruitment and importation of skills becoming crucial for construction companies to meet demand and compete effectively. This report presents 15 case studies from a range of organisations involved in the Canterbury rebuild, exploring the business dynamics and outcomes of their resourcing initiatives. A key finding of this research is that, for many construction organisations, resourcing initiatives have become part of their organisational longer-term development strategies, rather than simply a response to ‘supply and demand’ pressures. Organisations are not relying on any single resourcing solution to drive their growth but use a combination of initiatives to create lasting business benefits, such as cost savings, improved brand and reputation, a stable and productive workforce, enhanced efficiency and staff morale, as well as improved skill levels.
This presentation summarizes the development of high-resolution surficial soil velocity models in the Canterbury, New Zealand basin. Shallow (<30m) shear wave velocities were primarily computed based on a combination of a large database of over 15,000 cone penetration test (CPT) logs in and around Christchurch, and a recently-developed Christchurch-specific empirical correlation between soil shear wave velocity and CPT. Large active-source testing at 22 locations and ambient-wavefield surface wave and H/V testing at over 80 locations were utilized in combination with 1700 water well logs to constrain the inter-bedded stratigraphy and velocity of Quaternary sediments up to depths of several hundred meters. Finally, seismic reflection profiles and the ambient-wavefield surface wave data provide constraint on velocities from several hundred meters to several kilometres. At all depths, the high resolution data illustrates the complexity of the soil conditions in the region, and the developed 3D models are presently being used in broadband ground motion simulations to further interpret the observed strong ground motions in the 2010-2011 Canterbury earthquake sequence.
The New Zealand city of Christchurch suffered a series of devastating earthquakes in 2010-11 that changed the urban landscape forever. A new rebuilt city is now underway, largely based on the expressed wishes of the populace to see Christchurch return to being a more people-oriented, cycle-friendly city that it was known for in decades past. Currently 7% of commuters cycle to work, supported by a 200km network of mostly conventional on-road painted cycle lanes and off-road shared paths. The new "Major Cycleways" plan aims to develop approximately 100km of high-quality cycling routes throughout the city in 5-7 years. The target audience is an unaccompanied 10-year-old cycling, which requires more separated cycleways and low-volume/speed "neighbourhood greenways" to meet this standard. This presentation summarises the steps undertaken to date to start delivering this network. Various pieces of research have helped to identify the types of infrastructure preferred by those currently not regularly cycling, as well as helping to assess the merits of different route choices. Conceptual cycleway guidelines have now been translated into detailed design principles for the different types of infrastructure being planned. While much of this work is based on successful designs from overseas, including professional advice from Dutch practitioners, an interesting challenge has been to adapt these designs as required to suit local road environments and road user expectations. The first parts of the new network are being rolled out now, with the hope that this will produce an attractive and resilient network for the future population that leads to cycling being a major part of the local way of life.
