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Research papers, University of Canterbury Library

Unreinforced masonry (URM) structures comprise a majority of the global built heritage. The masonry heritage of New Zealand is comparatively younger to its European counterparts. In a country facing frequent earthquakes, the URM buildings are prone to extensive damage and collapse. The Canterbury earthquake sequence proved the same, causing damage to over _% buildings. The ability to assess the severity of building damage is essential for emergency response and recovery. Following the Canterbury earthquakes, the damaged buildings were categorized into various damage states using the EMS-98 scale. This article investigates machine learning techniques such as k-nearest neighbors, decision trees, and random forests, to rapidly assess earthquake-induced building damage. The damage data from the Canterbury earthquake sequence is used to obtain the forecast model, and the performance of each machine learning technique is evaluated using the remaining (test) data. On getting a high accuracy the model is then run for building database collected for Dunedin to predict expected damage during the rupture of the Akatore fault.

Research papers, University of Canterbury Library

Light timber framed (LTF) structures provide a cost-effective and structurally efficient solution for low-rise residential buildings. This paper studies seismic performance of single-storey LTF buildings sheathed by gypsum-plasterboards (GPBs) that are a typical lining product in New Zealand houses. Compared with wood-based structural panels, GPBs tend to be more susceptible to damage when they are used in bracing walls to resist earthquake loads. This study aims to provide insights on how the bracing wall irregularity allowed by the current New Zealand standard NZS 3604 and the in-plane rigidity of ceiling diaphragms affect the overall seismic performance of these GPB-braced LTF buildings. Nonlinear time-history analyses were conducted on a series of single-storey baseline buildings with different levels of bracing wall irregularities and ceiling diaphragm rigidity. The results showed significant torsional effect caused by the eccentric bracing wall layout with semi-rigid/rigid ceiling diaphragms. On average, bracing wall drift demand caused by the extreme bracing wall irregularities was three times of that in the regular bracing wall layout under the rigid diaphragm assumption. This finding agreed well with the house survey after the 2011 Canterbury Earthquake in which significantly more damage was observed in the houses with irregular bracing wall layouts and relatively rigid diaphragms. Therefore, it is recommended to limit the level of bracing wall eccentricity and ensure the sufficiently rigid diaphragms to avoid excessive damage in these LTF buildings in future events.

Research papers, University of Canterbury Library

There is an increasing recognition that the seismic performance of buildings will be affected by the behaviour of both structural and non-structural elements. In light of this, work has been progressing at the University of Canterbury to develop guidelines for the seismic assessment of commercial glazing systems. This paper reviews the seismic assessment guidelines prescribed in Section C10 of the MBIE building assessment guidelines. Subsequently, the C10 approach is used to assess the drift capacity of a number of glazing units recently tested at the University of Canterbury. Comparing the predicted and observed drift capacities, it would appear that the C10 guidelines may lead to nonconservative estimates of drift capacity. Furthermore, the experimental results indicate that watertightness may be lost at very low drift demands, suggesting that guidance for the assessment of serviceability performance would also be beneficial. As such, it is proposed that improved guidance be provided to assist engineers in considering the possible impact that glazing could have on the structural response of a building in a large earthquake.

Research papers, University of Canterbury Library

Glazing systems are non-structural elements in a building that, more often than not, appear to be given little consideration in seismic design. Recent experimental work into glazing systems at the University of Canterbury, however, has shown that glazing systems can be very susceptible to serviceability damage, defined as loss of water-tightness. The focus of this paper is to highlight the difference in vulnerability of standard and seismic glazing systems and consider the implications of this for future repair costs and losses. The paper first describes the damage states chosen for glazing units according to the repair strategies required and expected repair costs. This includes three damage states: DS1: Water Leakage, DS2: Gasket Failure and DS3: Frame/Glass Failure. Implementing modern performance-based earthquake engineering, the paper proceeds to highlight a case study comparing costs and expected losses of a standard glazing unit and a seismic glazing unit installed on a case study building. It is shown that the use of seismic glazing units is generally beneficial over time, due to the early onset of serviceability damage in standard glazing units. Finally, the paper provides suggestions for designers aimed at reducing costs related to earthquake induced repairs of glazing.

Research papers, University of Canterbury Library

This analysis employs both qualitative and quantitative approaches to identify how young adults in New Zealand aged 18-25 years old have engaged with All Right? campaign material. A survey targeting young adults returned 51 viable out of 117 responses due to participation prerequisites. From the survey, five participants elaborated on their thoughts in an in-depth interview voluntarily. Interviews were conducted with key personnel from All Right? to craft broader understanding of the initiative whilst enhancing knowledge of mental health frameworks and their application. Ciaran Fox, Lucy Daeth and Sara Epperson, who have been imperative to the success of the campaign, shared their working experience in the community and public health sector and how this intertwines to their current roles at All Right?. Discussions of key frameworks, community conversations, the development of communication strategies and how All Right? approached Canterbury publics in a post-earthquake setting provided insight to the importance of understanding community circumstance in initial crisis and the correlated secondary stressors.

Research papers, University of Canterbury Library

Base isolation is an incredibly effective technology used in seismic regions throughout the world to limit structural damage and maintain building function, even after severe earthquakes. However, it has so far been underutilised in light-frame wood construction due to perceived cost issues and technical problems, such as a susceptibility to movement under strong wind loads. Light-frame wood buildings make up the majority of residential construction in New Zealand and sustained significant damage during the 2010-2011 Canterbury earthquake sequence, yet the design philosophy has remained largely unchanged for years due to proven life-safety performance. Recently however, with the advent of performance based earthquake engineering, there has been a renewed focus on performance factors such as monetary loss that has driven a want for higher performing residential buildings. This research develops a low-cost approach for the base isolation of light-frame wood buildings using a flat-sliding friction base isolation system, which addresses the perceived cost and technical issues, and verifies the seismic performance through physical testing on the shake table at the University of Canterbury. Results demonstrate excellent seismic performance with no structural damage reported despite a large number of high-intensity earthquake simulations. Numerical models are subsequently developed and calibrated to New Zealand light-frame wood building construction approaches using state-of-the-art wood modelling software, Timber3D. The model is used to accurately predict both superstructure drift and acceleration demand parameters of fixed-base testing undertaken after the base isolation testing programme is completed. The model development allows detailed cost analyses to be undertaken within the performance based earthquake engineering framework that highlights the monetary benefits of using base isolation. Cost assessments indicate the base isolation system is only 6.4% more compared to the traditional fixed-base system. Finally, a design procedure is recommended for base isolated light-frame wood buildings that is founded on the displacement based design (DBD) approach used in the United States and New Zealand. Nonlinear analyses are used to verify the DBD method which indicate its suitability.

Research papers, University of Canterbury Library

Over 6.3 million waste tyres are produced annually in New Zealand (Tyrewise, 2021), leading to socioeconomic and environmental concerns. The 2010-11 Canterbury Earthquake Sequence inflicted extensive damage to ~6,000 residential buildings, highlighting the need to improve the seismic resilience of the residential housing sector. A cost-effective and sustainable eco-rubber geotechnical seismic isolation (ERGSI) foundation system for new low-rise buildings was developed by the authors. The ERGSI system integrates a horizontal geotechnical seismic isolation (GSI) layer i.e., a deformable seismic energy dissipative filter made of granulated tyre rubber (GTR) and gravel (G) – and a flexible rubberised concrete raft footing. Geotechnical experimental and numerical investigations demonstrated the effectiveness of the ERGSI system in reducing the seismic demand at the foundation level (i.e., reduced peak ground acceleration) (Hernandez et al., 2019; Tasalloti et al., 2021). However, it is essential to ensure that the ERGSI system has minimal leaching attributes and does not result in long-term negative impacts on the environment.

Research papers, University of Canterbury Library

A number of reverse and strike-slip faults are distributed throughout mid-Canterbury, South Island, New Zealand, due to oblique continental collision. There is limited knowledge on fault interaction in the region, despite historical multi-fault earthquakes involving both reverse and strike-slip faults. The surface expression and paleoseismicity of these faults can provide insights into fault interaction and seismic hazards in the region. In this thesis, I studied the Lake Heron and Torlesse faults to better understand the key differences between these two adjacent faults located within different ‘tectonic domains’. Recent activity and surface expression of the Lake Heron fault was mapped and analysed using drone survey, Structure-from-Motion (SfM) derived Digital Surface Model (DSM), aerial image, 5 m-Digital Elevation Model (DEM), luminescence dating technique, and fold modelling. The results show a direct relationship between deformation zone width and the thickness of the gravel deposits in the area. Fold modelling using fault dip, net slip and gravel thickness produces a deformation zone comparable to the field, indicating that the fault geometry is sound and corroborating the results. This result Is consistent with global studies that demonstrate deposit (or soil thickness) correlates to fault deformation zone width, and therefore is important to consider for fault displacement hazard. A geomorphological study on the Torlesse fault was conducted using SfM-DSM, DEM and aerial images Ground Penetrating Radar (GPR) survey, trenching, and radiocarbon and luminescence dating. The results indicate that the Torlesse fault is primarily strike-slip with some dip slip component. In many places, the bedding-parallel Torlesse fault offsets post-glacial deposits, with some evidence of flexural slip faulting due to folding. Absolute dating of offset terraces using radiocarbon dating and slip on fault determined from lateral displacement calculating tool demonstrates the fault has a slip rate of around 0.5 mm/year to 1.0 mm/year. The likelihood of multi-fault rupture in the Torlesse Range has been characterised using paleoseismic trenching, a new structural model, and evaluation of existing paleoseismic data on the Porters Pass fault. Identification of overlapping of paleoseismic events in main Torlesse fault, flexural-slip faults and the Porters Pass fault in the Torlesse Range shows the possibility of distinct or multi-fault rupture on the Torlesse fault. The structural connectivity of the faults in the Torlesse zone forming a ‘flower structure’ supports the potential of multi-fault rupture. Multi-fault rupture modelling carried out in the area shows a high probability of rupture in the Porters Pass fault and Esk fault which also supports the co-rupture probability of faults in the region. This study offers a new understanding of the chronology, slip distribution, rupture characteristics and possible structural and kinematic relationship of Lake Heron fault and Torlesse fault in the South Island, New Zealand.

Research papers, University of Canterbury Library

Researchers have begun to explore the opportunity presented by blue-green infrastructure(a subset of nature-based solutions that provide blue and green space in urban infrastructure)as a response to the pressures of climate change. The 2010/2011 Canterbury earthquake sequence created a unique landscape within which there is opportunity to experiment with and invest in new solutions to climate change adaptation in urban centres. Constructed wetlands are an example of blue-green infrastructure that can potentially support resilience in urban communities. This research explores interactions between communities and constructed wetlands to understand how this may influence perceptions of community resilience. The regeneration of the Ōtākaro Avon River Corridor (OARC) provides a space to investigate these relationships. Seven stakeholders from the community, industry, and academia, each with experience in blue-green infrastructure in the OARC, participated in a series of semi-structured interviews. Each participant was given the opportunity to reflect on their perspectives of community, community resilience, and constructed wetlands and their interconnections. Interview questions aligned with the overarching research objectives to (1) understand perceptions around the role of wetlands in urban communities, (2) develop a definition for community resilience in the context of the Ōtākaro Avon community, and (3) reflect on how wetlands can contribute to (or detract from) community resilience. This study found that constructed wetlands can facilitate learning about the challenges and solutions needed to adapt to climate change. From the perspective of the community representatives, community resilience is linked to social capital. Strong social networks and a relationship with nature were emphasised as core components of a community’s ability to adapt to disruption. Constructed wetlands are therefore recognised as potentially contributing to community resilience by providing spaces for people to engage with each other and nature. Investment in constructed wetlands can support a wider response to climate change impacts. This research was undertaken with the support of the Ōtākaro Living Laboratory Trust, who are invested in the future of the OARC. The outcomes of this study suggest that there is an opportunity to use wetland spaces to establish programmes that explore the perceptions of constructed wetlands from a broader community definition, at each stage of the wetland life cycle, and at wider scales(e.g., at a city scale or beyond).

Research papers, University of Canterbury Library

Liquefaction is a phenomenon that results in a loss of strength and stability of a saturated soil mass due to dynamic excitation such as that imposed by an earthquake. The granular nature of New Zealand soils and the location of many of our cities and towns on fluvial foundations are such that the effects of liquefaction can be very important. Research was undertaken to build on the past work undertaken at the University of Canterbury studying the effects of the 1929 Murchison earthquake, the 1968 Inangahua earthquake and the 1991 Hawks Crag earthquakes on the West Coast. Additional archival information has been gathered from newspapers and reports and from discussions with people who experienced one or all of these large earthquakes that occurred on the West Coast during the 20th Century. Further, some twenty Cone Penetrometer Tests were carried out, with varying success, in Greymouth and Karamea using the Department of Civil Engineering's Drilling Rig. These, combined with the basic site investigation information, consolidate and add to the liquefaction case history data bank at the University of Canterbury. Many of the sites have liquefied in some but not all of the three earthquakes and thus provide both upper and lower bounds for the calibration of empirical models. While a lack of knowledge of the 1929 source location reduces the value of information from that event, the data form a useful set of liquefaction case histories and will become more so as further earthquakes occur. A list of critical sites for checking of the future earthquakes is provided and recommendations are made for the installation of downhole arrays of accelerometers and pore water pressure transducers at a number of sites.

Research papers, University of Canterbury Library

Landslides are significant hazards, especially in seismically-active mountainous regions, where shaking amplified by steep topography can result in widespread landsliding. These landslides present not only an acute hazard, but a chronic hazard that can last years-to-decades after the initial earthquake, causing recurring impacts. The Mw 7.8 Kaikōura earthquake caused more than 20,000 landslides throughout North Canterbury and resulted in significant damage to nationally significant infrastructure in the coastal transport corridor (CTC), isolating Kaikōura from the rest of New Zealand. In the years following, ongoing landsliding triggered by intense rainfall exacerbated the impacts and slowed the recovery process. However, while there is significant research on co-seismic landslides and their initial impacts in New Zealand, little research has explored the evolution of co-seismic landslides and how this hazard changes over time. This research maps landslides annually between 2013 and 2021 to evaluate the changes in pre-earthquake, co-seismic and post-earthquake rates of landsliding to determine how landslide hazard has changed over this time. In particular, the research explores how the number, area, and spatial distribution of landslides has changed since the earthquake, and whether post-earthquake mitigation works have in any way affected the long-term landslide hazard. Mapping of landslides was undertaken using open-source, medium resolution Landsat-8 and Sentinel-2 satellite imagery, with landslides identified visually and mapped as single polygons that capture both the source zone and deposit. Three study areas with differing levels of post-earthquake mitigation are compared: (i) the northern CTC, where the majority of mitigation was in the form of active debris removal; (ii) the southern CTC, where mitigation was primarily via passive protection measures; and (iii) Mount Fyffe, which has had no mitigation works since the earthquake. The results show that despite similar initial impacts during the earthquake, the rate of recovery in terms of landslide rates varies substantially across the three study areas. In Mount Fyffe, the number and area of landslides could take 45 and 22 years from 2021 respectively to return to pre-earthquake levels at the current rate. Comparatively, in the CTC, it could take just 5 years and 3-4 years from 2021 respectively. Notably, the fastest recovery in terms of landslide rates in the CTC was primarily located directly along the transport network, whereas what little recovery did occur in Mount Fyffe appeared to follow no particular pattern. Importantly, recovery rates in the northern CTC were notably higher than in the southern CTC, despite greater co-seismic impacts in the former. Combined, these results suggest the active, debris removal mitigation undertaken in the northern CTC may have had the effect of dramatically reducing the time for landslide rates to return to pre-earthquake levels. The role of slope angle and slope aspect were explored to evaluate if these observations could be driven by local differences in topography. The Mount Fyffe study area has higher slope angles than the CTC as a whole and landslides predominantly occurred on slightly steeper slopes than in the CTC. This may have contributed to the longer recovery times for landsliding in Mount Fyffe due to greater gravitational instability, however the observed variations are minor compared to the differences in recovery rates. In terms of slope aspect, landslides in Mount Fyffe preferentially occurred on north- and south-facing slopes whereas landslides in the CTC preferred the east- and south-facing slopes. The potential role of these differences in landslide recovery remains unclear but may be related to the propagation direction of the earthquake and the tracking direction of post-earthquake ex-tropical cyclones. Finally, landslides in the CTC are observed to be moving further away from the transport network and the number of landslides impacting the CTC decreased significantly since the earthquake. Nevertheless, the potential for further landslide reactivation remains. Therefore, despite the recovery in the CTC, it is clear that there is still risk of the transport network being impacted by further landsliding, at least for the next 3-5 yrs.

Research papers, University of Canterbury Library

People aged 65 years and older are the fastest growing age group in New Zealand. By the mid-2070s, there are predictions that this age group is likely to comprise approximately one third of the population. Older people are encouraged to stay in their own homes within their community for as long as possible with support to encourage the extension of ageing in place. Currently around 14% of those aged 75 years or older, make the move into retirement villages. This is expected to increase. Little is known by retirement villages about the wellbeing and health of those who decide to live independently in these facilities. Predicting the need for a continuum of care is challenging. This research measured the wellbeing and health of older adults. It was situated in a critical realist paradigm, overlaid with an empathetic axiology. A focused literature review considered the impact on wellbeing from the aspects of living place, age, gender, health status and the 2010/2011 Canterbury earthquakes. Longitudinal studies used the Enlightenment Scale and the interRAI Community Health Assessment (CHA) to measure the wellbeing and health of one group of residents (n=120) living independently in one retirement village in Canterbury, New Zealand. The research was extended to incorporate two cross-section studies when initial results for wellbeing were found to be higher than anticipated. These additional studies included participants living independently from other retirement villages (n=115) and those living independently within the community (n=354). A total of 589 participants, aged 65 – 97 years old, completed the Enlightenment Scale across the four studies. Across the living places, wellbeing continued to significantly improve with age. The Enlightenment Scale was a useful measure of wellbeing with older adults. Participants in the longitudinal studies largely maintained a relatively good health status, showing little change over the study period of 15 months. Predictions for the need for a move to supportive care were not able to be made using the CHA. The health status of participants did not influence their level of wellbeing. The key finding of note is that the wellbeing score of older adults increases by 1.27 points per year, using the Enlightenment Scale, irrespective of where they live.

Research papers, University of Canterbury Library

In this article we utilize grounded theory to explore women’s experiences in the unique construction industry context that followed the 2010 Canterbury (New Zealand) earthquakes. Data were obtained from 36 semi-structured interviews conducted with women working in a variety of occupations in the construction industry. We identify three inter-related categories: capitalizing on opportunity, demonstrating capability and surface tolerance, which together represent a response process that we label ‘deferential tailoring’. The deferential tailoring process explains how women intentionally shape their response to industry conditions through self-regulating behaviors that enables them to successfully seize opportunities and manage gender-related challenges in the working environment. Our findings challenge existing research which suggests that women adopt submissive coping strategies to conform to androcentric norms in the construction industry. Instead, we argue that the process of deferential tailoring can empower women to build positive workplace relationships, enhance career development, and help shift perceptions of the value of their work in the industry.

Research papers, University of Canterbury Library

In 2016, the Building (Earthquake-prone Buildings) Amendment Act 2016 was introduced to address the issue of seismic vulnerability amongst existing buildings in Aotearoa New Zealand. This Act introduced a mandatory scheme to remediate buildings deemed particularly vulnerable to seismic hazard, as recommended by the 2012 Royal Commission into the Canterbury earthquake sequence of 2010–2011. This Earthquake-prone Building (EPB) framework is unusual internationally for the mandatory obligations that it introduces. This article explores and critiques the operation of the scheme in practice through an examination of its implementation provisions and the experiences of more recent seismic events (confirmed by engineering research). This analysis leads to the conclusion that the operation of the current scheme and particularly the application of the concept of EPB vulnerability excludes large numbers of (primarily urban) buildings which pose a significant risk in the event of a significant (but expected) seismic event. As a result, the EPB scheme fails to achieve its goals and instead may create a false impression that it does so

Research papers, University of Canterbury Library

Recent surface-rupturing earthquakes in New Zealand have highlighted significant exposure and vulnerability of the road network to fault displacement. Understanding fault displacement hazard and its impact on roads is crucial for mitigating risks and enhancing resilience. There is a need for regional-scale assessments of fault displacement to identify vulnerable areas within the road network for the purposes of planning and prioritising site-specific investigations. This thesis employs updated analysis of data from three historical surface-rupturing earthquakes (Edgecumbe 1987, Darfield 2010, and Kaikoūra 2016) to develop an empirical model that addresses the gap in regional fault displacement hazard analysis. The findings contribute to understanding of • How to use seismic hazard model inputs for regional fault displacement hazard analysis • How faulting type and sediment cover affects the magnitude and spatial distribution of fault displacement • How the distribution of displacement and regional fault displacement hazard is impacted by secondary faulting • The inherent uncertainties and limitations associated with employing an empirical approach at a regional scale • Which sections of New Zealand’s roading network are most susceptible to fault displacement hazard and warrant site-specific investigations • Which regions should prioritise updating emergency management plans to account for post-event disruptions to roading. I used displacement data from the aforementioned historical ruptures to generate displacement versus distance-to-fault curves for various displacement components, fault types, and geological characteristics. Using those relationships and established relationships for along-strike displacement, displacement contours were generated surrounding active faults within the NZ Community Fault Model. Next, I calculated a new measure of 1D strain along roads as well as relative hazard, which integrated 1D strain and normalised slip rate data. Summing these values at the regional level identified areas of heightened relative hazard across New Zealand, and permits an assessment of the susceptibility of road networks using geomorphon land classes as proxies for vulnerability. The results reveal that fault-parallel displacements tend to localise near the fault plane, while vertical and fault-perpendicular displacements sustain over extended distances. Notably, no significant disparities were observed in off-fault displacement between the hanging wall and footwall sides of the fault, or among different surface geology types, potentially attributed to dataset biases. The presence of secondary faulting in the dataset contributes to increased levels of tectonic displacement farther from the fault, highlighting its significance in hazard assessments. Furthermore, fault displacement contours delineate broader zones around dip-slip faults compared to strike-slip faults, with correlations identified between fault length and displacement width. Road ‘strain’ values are higher around dip-slip faults, with notable examples observed in the Westland and Buller Districts. As expected, relative hazard analysis revealed elevated values along faults with high slip rates, notably along the Alpine Fault. A regional-scale analysis of hazard and exposure reveals heightened relative hazard in specific regions, including Wellington, Southern Hawke’s Bay, Central Bay of Plenty, Central West Coast, inland Canterbury, and the Wairau Valley of Marlborough. Notably, the Central West Coast exhibits the highest summed relative hazard value, attributed to the fast-slipping Alpine Fault. The South Island generally experiences greater relative hazard due to larger and faster-slipping faults compared to the North Island, despite having fewer roads. Central regions of New Zealand face heightened risk compared to Southern or Northern regions. Critical road links intersecting high-slipping faults, such as State Highways 6, 73, 1, and 2, necessitate prioritisation for site-specific assessments, emergency management planning and targeted mitigation strategies. Roads intersecting with the Alpine Fault are prone to large parallel displacements, requiring post-quake repair efforts. Mitigation strategies include future road avoidance of nearby faults, modification of road fill and surface material, and acknowledgement of inherent risk, leading to prioritised repair efforts of critical roads post-quake. Implementing these strategies enhances emergency response efforts by improving accessibility to isolated regions following a major surface-rupturing event, facilitating faster supply delivery and evacuation assistance. This thesis contributes to the advancement of understanding fault displacement hazard by introducing a novel regional, empirical approach. The methods and findings highlight the importance of further developing such analyses and extending them to other critical infrastructure types exposed to fault displacement hazard in New Zealand. Enhancing our comprehension of the risks associated with fault displacement hazard offers valuable insights into various mitigation strategies for roading infrastructure and informs emergency response planning, thereby enhancing both national and global infrastructure resilience against geological hazards.

Images, UC QuakeStudies

Dean Manson photographed in an eastern riverside suburb. Dean is a UC graduate who travelled down from Palmerston North to help with the Farmy Army and Student Volunteer Army. He was scouting jobs in the morning before the arrival of volunteers.