The Canterbury earthquakes resulted in numerous changes to the waterways of Ōtautahi Christchurch. These included bank destabilisation, liquefaction effects, changes in bed levels, and associated effects on flow regimes and inundation levels. This study set out to determine if these effects had altered the location and pattern of sites utilised by īnanga (Galaxias maculatus) for spawning, which are typically restricted to very specific locations in upper estuarine areas. Extensive surveys were carried out in the Heathcote/Ōpāwaho and Avon/Ōtākaro catchments over the four peak months of the 2015 spawning season. New spawning sites were found in both rivers and analysis against pre-earthquake records identified that other significant changes have occurred. Major changes include the finding of many new spawning sites in the Heathcote/Ōpāwaho catchment. Sites now occur up to 1.5km further downstream than the previously reported limit and include the first records of spawning below the Woolston Cut. Spawning sites in the Avon/Ōtākaro catchment also occur in new locations. In the mainstem, sites now occur both upstream and downstream of all previously reported locations. A concentrated area of spawning was identified in Lake Kate Sheppard at a distinctly different location versus pre-quake records, and no spawning was found on the western shores. Spawning was also recorded for the first time in Anzac Creek, a nearby waterway connected to Lake Kate Sheppard via a series of culverts.
Overview of SeisFinder SeisFinder is an open-source web service developed by QuakeCoRE and the University of Canterbury, focused on enabling the extraction of output data from computationally intensive earthquake resilience calculations. Currently, SeisFinder allows users to select historical or future events and retrieve ground motion simulation outputs for requested geographical locations. This data can be used as input for other resilience calculations, such as dynamic response history analysis. SeisFinder was developed using Django, a high-level python web framework, and uses a postgreSQL database. Because our large-scale computationally-intensive numerical ground motion simulations produce big data, the actual data is stored in file systems, while the metadata is stored in the database. The basic SeisFinder architecture is shown in Figure 1.
The purpose of this thesis is to conduct a detailed examination of the forward-directivity characteristics of near-fault ground motions produced in the 2010-11 Canterbury earthquakes, including evaluating the efficacy of several existing empirical models which form the basis of frameworks for considering directivity in seismic hazard assessment. A wavelet-based pulse classification algorithm developed by Baker (2007) is firstly used to identify and characterise ground motions which demonstrate evidence of forward-directivity effects from significant events in the Canterbury earthquake sequence. The algorithm fails to classify a large number of ground motions which clearly exhibit an early-arriving directivity pulse due to: (i) incorrect pulse extraction resulting from the presence of pulse-like features caused by other physical phenomena; and (ii) inadequacy of the pulse indicator score used to carry out binary pulse-like/non-pulse-like classification. An alternative ‘manual’ approach is proposed to ensure 'correct' pulse extraction and the classification process is also guided by examination of the horizontal velocity trajectory plots and source-to-site geometry. Based on the above analysis, 59 pulse-like ground motions are identified from the Canterbury earthquakes , which in the author's opinion, are caused by forward-directivity effects. The pulses are also characterised in terms of their period and amplitude. A revised version of the B07 algorithm developed by Shahi (2013) is also subsequently utilised but without observing any notable improvement in the pulse classification results. A series of three chapters are dedicated to assess the predictive capabilities of empirical models to predict the: (i) probability of pulse occurrence; (ii) response spectrum amplification caused by the directivity pulse; (iii) period and amplitude (peak ground velocity, PGV) of the directivity pulse using observations from four significant events in the Canterbury earthquakes. Based on the results of logistic regression analysis, it is found that the pulse probability model of Shahi (2013) provides the most improved predictions in comparison to its predecessors. Pulse probability contour maps are developed to scrutinise observations of pulses/non-pulses with predicted probabilities. A direct comparison of the observed and predicted directivity amplification of acceleration response spectra reveals the inadequacy of broadband directivity models, which form the basis of the near-fault factor in the New Zealand loadings standard, NZS1170.5:2004. In contrast, a recently developed narrowband model by Shahi & Baker (2011) provides significantly improved predictions by amplifying the response spectra within a small range of periods. The significant positive bias demonstrated by the residuals associated with all models at longer vibration periods (in the Mw7.1 Darfield and Mw6.2 Christchurch earthquakes) is likely due to the influence of basin-induced surface waves and non-linear soil response. Empirical models for the pulse period notably under-predict observations from the Darfield and Christchurch earthquakes, inferred as being a result of both the effect of nonlinear site response and influence of the Canterbury basin. In contrast, observed pulse periods from the smaller magnitude June (Mw6.0) and December (Mw5.9) 2011 earthquakes are in good agreement with predictions. Models for the pulse amplitude generally provide accurate estimates of the observations at source-to-site distances between 1 km and 10 km. At longer distances, observed PGVs are significantly under-predicted due to their slower apparent attenuation. Mixed-effects regression is employed to develop revised models for both parameters using the latest NGA-West2 pulse-like ground motion database. A pulse period relationship which accounts for the effect of faulting mechanism using rake angle as a continuous predictor variable is developed. The use of a larger database in model development, however does not result in improved predictions of pulse period for the Darfield and Christchurch earthquakes. In contrast, the revised model for PGV provides a more appropriate attenuation of the pulse amplitude with distance, and does not exhibit the bias associated with previous models. Finally, the effects of near-fault directivity are explicitly included in NZ-specific probabilistic seismic hazard analysis (PSHA) using the narrowband directivity model of Shahi & Baker (2011). Seismic hazard analyses are conducted with and without considering directivity for typical sites in Christchurch and Otira. The inadequacy of the near-fault factor in the NZS1170.5: 2004 is apparent based on a comparison with the directivity amplification obtained from PSHA.
Liquefaction-induced lateral spreading in Christchurch and surrounding suburbs during the recent Canterbury Earthquake Sequence (2010-2011) caused significant damage to structures and lifelines located in close proximity to streams and rivers. Simplified methods used in current engineering practice for predicting lateral ground displacements exhibit a high degree of epistemic uncertainty, but provide ‘order of magnitude’ estimates to appraise the hazard. We wish to compare model predictions to field measurements in order to assess the model’s capabilities and limitations with respect to Christchurch conditions. The analysis presented focuses on the widely-used empirical model of Youd et al. (2002), developed based on multi-linear regression (MLR) of case history data from lateral spreading occurrence in Japan and the US. Two issues arising from the application of this model to Christchurch were considered: • Small data set of Standard Penetration Test (SPT) and soil gradation indices (fines content FC, and mean grain size, D50) required for input. We attempt to use widely available CPT data with site specific correlations to FC and D50. • Uncertainty associated with the model input parameters and their influence on predicted displacements. This has been investigated for a specific location through a sensitivity analysis.
The Stone Jug Fault (SJF) ruptured during the November 14th, 2016 (at 12:02 am), Mw 7.8 Kaikōura Earthquake which initiated ~40 km west-southwest of the study area, at a depth of approximately 15 km. Preliminary post-earthquake mapping indicated that the SJF connects the Conway-Charwell and Hundalee faults, which form continuous surface rupture, however, detailed study of the SJF had not been undertaken prior to this thesis due to its remote location and mountainous topography. The SJF is 19 km long, has an average strike of ~160° and generally carries approximately equal components of sinistral and reverse displacement. The primary fault trace is sigmoidal in shape with the northern and southern tips rotating in strike from NNW to NW, as the SJF approaches the Hope and Hundalee faults. It comprises several steps and bends and is associated with many (N=48) secondary faults, which are commonly near irregularities in the main fault geometry and in a distributed fault zone at the southern tip. The SJF is generally parallel to Torlesse basement bedding where it may utilise pre-existing zones of weakness. Horizontal, vertical and net displacements range up to 1.4 m, with displacement profiles along the primary trace showing two main maxima separated by a minima towards the middle and ends of the fault. Average net displacement along the primary trace is ~0.4m, with local changes in relative values of horizontal and vertical displacement at least partly controlled by fault strike. Two trenches excavated across the northern segment of the fault revealed displacement of mainly Holocene stratigraphy dated using radiocarbon (N=2) and OSL (N=4) samples. Five surface-rupturing paleoearthquakes displaying vertical displacements of <1 m occurred at: 11,000±1000, 7500±1000, 6500±1000, 3500±100 and 3 (2016 Kaikōura) years BP. These events produce an average slip rate since ~11 ka of 0.2-0.4 mm/yr and recurrence intervals of up to 5500 years with an average recurrence interval of 2750 yrs. Comparison of these results with unpublished trench data suggests that synchronous rupture of the Hundalee, Stone Jug, Conway-Charwell, and Humps faults at ~3500 yrs BP cannot be discounted and it is possible that multi-fault ruptures in north Canterbury are more common than previously thought.
Coastal margins are exposed to rising sea levels that present challenging circumstances for natural resource management. This study investigates a rare example of tectonic displacement caused by earthquakes that generated rapid sea-level change in a tidal lagoon system typical of many worldwide. This thesis begins by evaluating the coastal squeeze effects caused by interactions between relative sea-level (RSL) rise and the built environment of Christchurch, New Zealand, and also examples of release from similar effects in areas of uplift where land reclamations were already present. Quantification of area gains and losses demonstrated the importance of natural lagoon expansion into areas of suitable elevation under conditions of RSL rise and showed that they may be necessary to offset coastal squeeze losses experienced elsewhere. Implications of these spatial effects include the need to provide accommodation space for natural ecosystems under RSL rise, yet other land-uses are likely to be present in the areas required. Consequently, the resilience of these environments depends on facilitating transitions between human land-uses either proactively or in response to disaster events. Principles illustrated by co-seismic sea-level change are generally applicable to climate change adaptation due to the similarity of inundation effects. Furthermore, they highlight the potential role of non-climatic factors in determining the overall trajectory of change. Chapter 2 quantifies impacts on riparian wetland ecosystems over an eight year period post- quake. Coastal wetlands were overwhelmed by RSL rise and recovery trajectories were surprisingly slow. Four risk factors were identified from the observed changes: 1) the encroachment of anthropogenic land-uses, 2) connectivity losses between areas of suitable elevation, 3) the disproportionate effect of larger wetland vulnerabilities, and 4) the need to protect new areas to address the future movement of ecosystems. Chapter 3 evaluates the unique context of shoreline management on a barrier sandspit under sea-level rise. A linked scenario approach was used to evaluate changes on the open coast and estuarine shorelines simultaneously and consider combined effects. The results show dune loss from a third of the study area using a sea-level rise scenario of 1 m over 100 years and with continuation of current land-uses. Increased exposure to natural hazards and accompanying demand for seawalls is a likely consequence unless natural alternatives can be progressed. In contrast, an example of managed retreat following earthquake-induced subsidence of the backshore presents a new opportunity to restart saltmarsh accretion processes seaward of coastal defences with the potential to reverse decades of degradation and build sea-level rise resilience. Considering both shorelines simultaneously highlights the existence of pinch-points from opposing forces that result in small land volumes above the tidal range. Societal adaptation is delicately poised between the paradigms of resisting or accommodating nature and challenged by the long perimeter and confined nature of the sandspit feature. The remaining chapters address the potential for salinity effects caused by tidal prism changes with a focus on the conservation of īnanga (Galaxias maculatus), a culturally important fish that supports New Zealand‘s whitebait fishery. Methodologies were developed to test the hypothesis that RSL changes would drive a shift in the distribution of spawning sites with implications for their management. Chapter 4 describes a new practical methodology for quantifying the total productivity and spatiotemporal variability of spawning sites at catchment scale. Chapter 5 describes the novel use of artificial habitats as a detection tools to help overcome field survey limitations in degraded environments where egg mortality can be high. The results showed that RSL changes resulted in major shifts in spawning locations and these were associated with new patterns of vulnerability due to the continuation of pre-disturbance land-uses. Unexpected findings includes an improved understanding of the spatial relationship between salinity and spawning habitat, and identification of an invasive plant species as important spawning habitat, both with practical management implications. To conclude, the design of legal protection mechanisms was evaluated in relation to the observed habitat shifts and with a focus on two new planning initiatives that identified relatively large protected areas (PAs) in the lower river corridors. Although the larger PAs were better able to accommodate the observed habitat shifts inefficiencies were also apparent due to spatial disparities between PA boundaries and the values requiring protection. To reduce unnecessary trade-offs with other land-uses, PAs of sufficient size to cover the observable spatiotemporal variability and coupled with adaptive capacity to address future change may offer a high effectiveness from a network of smaller PAs. The latter may be informed by both monitoring and modelling of future shifts and these are expected to include upstream habitat migration driven by the identified salinity relationships and eustatic sea-level rise. The thesis concludes with a summary of the knowledge gained from this research that can assist the development of a new paradigm of environmental sustainability incorporating conservation and climate change adaptation. Several promising directions for future research identified within this project are also discussed.
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Tsunami events including the 2004 Indian Ocean Tsunami and the 2011 Tohoku Earthquake and Tsunami confirmed the need for Pacific-wide comprehensive risk mitigation and effective tsunami evacuation planning. New Zealand is highly exposed to tsunamis and continues to invest in tsunami risk awareness, readiness and response across the emergency management and science sectors. Evacuation is a vital risk reduction strategy for preventing tsunami casualties. Understanding how people respond to warnings and natural cues is an important element to improving evacuation modelling techniques. The relative rarity of tsunami events locally in Canterbury and also globally, means there is limited knowledge on tsunami evacuation behaviour, and tsunami evacuation planning has been largely informed by hurricane evacuations. This research aims to address this gap by analysing evacuation behaviour and movements of Kaikōura and Southshore/New Brighton (coastal suburb of Christchurch) residents following the 2016 Kaikōura earthquake. Stage 1 of the research is engaging with both these communities and relevant hazard management agencies, using a survey and community workshops to understand real-event evacuation behaviour during the 2016 Kaikōura earthquake and subsequent tsunami evacuations. The second stage is using the findings from stage 1 to inform an agent-based tsunami evacuation model, which is an approach that simulates of the movement of people during an evacuation response. This method improves on other evacuation modelling approaches to estimate evacuation times due to better representation of local population characteristics. The information provided by the communities will inform rules and interactions such as traffic congestion, evacuation delay times and routes taken to develop realistic tsunami evacuation models. This will allow emergency managers to more effectively prepare communities for future tsunami events, and will highlight recommended actions to increase the safety and efficiency of future tsunami evacuations.
The use of post-earthquake cordons as a tool to support emergency managers after an event has been documented around the world. However, there is limited research that attempts to understand the use, effectiveness, inherent complexities, impacts and subsequent consequences of cordoning once applied. This research aims to fill that gap by providing a detailed understanding of first, the cordons and associated processes, and their implications in a post-earthquake scenario. We use a qualitative method to understand cordons through case studies of two cities where it was used in different temporal and spatial scales: Christchurch (2011) and Wellington (Kaikōura earthquake 2016), New Zealand. Data was collected through 21 expert interviews obtained through purposive and snowball sampling of key informants who were directly or indirectly involved in a decision-making role and/or had influence in relation to the cordoning process. The participants were from varying backgrounds and roles i.e. emergency managers, council members, business representatives, insurance representatives, police and communication managers. The data was transcribed, coded in Nvivo and then grouped based on underlying themes and concepts and then analyzed inductively. It is found that cordons are used primarily as a tool to control access for the purpose of life safety and security. But cordons can also be adapted to support recovery. Broadly, it can be synthesized and viewed based on two key aspects, ‘decision-making’ and ‘operations and management’, which overlap and interact as part of a complex system. The underlying complexity arises in large part due to the multitude of sectors it transcends such as housing, socio-cultural requirements, economics, law, governance, insurance, evacuation, available resources etc. The complexity further increases as the duration of cordon is extended.
Decision making on the reinstatement of the Christchurch sewer system after the Canterbury (New Zealand) earthquake sequence in 2010–2011 relied strongly on damage data, in particular closed circuit television (CCTV). This paper documents that process and considers how data can influence decision making. Data are analyzed on 33,000 pipes and 13,000 repairs and renewals. The primary findings are that (1) there should be a threshold of damage per pipe set to make efficient use of CCTV; (2) for those who are estimating potential damage, care must be taken in direct use of repair data without an understanding of the actual damage modes; and (3) a strong correlation was found between the ratio of faults to repairs per pipe and the estimated peak ground velocity. Taken together, the results provide evidence of the extra benefit that damage data can provide over repair data for wastewater networks and may help guide others in the development of appropriate strategies for data collection and wastewater pipe decisions after disasters.
This paper investigates the effects of variability in source rupture parameters on site-specific physics-based simulated ground motions, ascertained through the systematic analysis of ground motion intensity measures. As a preliminary study, we consider simulations of the 22 February 2011 Christchurch earthquake using the Graves and Pitarka (2015) methodology. The effects of source variability are considered via a sensitivity study in which parameters (hypocentre location, earthquake magnitude, average rupture velocity, fault geometry and the Brune stress parameter) are individually varied by one standard deviation. The sensitivity of simulated ground motion intensity measures are subsequently compared against observational data. The preliminary results from this study indicate that uncertainty in the stress parameter and the rupture velocity have the most significant effect on the high frequency amplitudes. Conversely, magnitude uncertainty was found to be most influential on the spectral acceleration amplitudes at low frequencies. Further work is required to extend this preliminary study to exhaustively consider more events and to include parameter covariance. The ultimate results of this research will assist in the validation of the overall simulation method’s accuracy in capturing various rupture parameters, which is essential for the use of simulated ground motion models in probabilistic seismic hazard analysis.
Shaking table testing of a full-scale three storey resilient and reparable complete composite steel framed building system is being conducted. The building incorporates a number of interchangeable seismic resisting systems of New Zealand and Chinese origin. The building has a steel frame and cold formed steel-concrete composite deck. Energy is dissipated by means of friction connections. These connections are arranged in a number of structural configurations. Typical building non-skeletal elements (NSEs) are also included. Testing is performed on the Jiading Campus shaking table at Tongji University, Shanghai, China. This RObust BUilding SysTem (ROBUST) project is a collaborative China-New Zealand project sponsored by the International Joint Research Laboratory of Earthquake Engineering (ILEE), Tongji University, and a number of agencies and universities within New Zealand including the BRANZ, Comflor, Earthquake Commission, HERA, QuakeCoRE, QuakeCentre, University of Auckland, and the University of Canterbury. This paper provides a general overview of the project describing a number of issues encountered in the planning of this programme including issues related to international collaboration, the test plan, and technical issues.
In response to the February 2011 earthquake, Parliament enacted the Canterbury Earthquake Recovery Act. This emergency legislation provided the executive with extreme powers that extended well beyond the initial emergency response and into the recovery phase. Although New Zealand has the Civil Defence Emergency Management Act 2002, it was unable to cope with the scale and intensity of the Canterbury earthquake sequence. Considering the well-known geological risk facing the Wellington region, this paper will consider whether a standalone “Disaster Recovery Act” should be established to separate an emergency and its response from the recovery phase. Currently, Government policy is to respond reactively to a disaster rather than proactively. In a major event, this typically involves the executive being given the ability to make rules, regulations and policy without the delay or oversight of normal legislative process. In the first part of this paper, I will canvas what a “Disaster Recovery Act” could prescribe and why there is a need to separate recovery from emergency. Secondly, I will consider the shortfalls in the current civil defence recovery framework which necessitates this kind of heavy governmental response after a disaster. In the final section, I will examine how
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.
The Master of Engineering Management Project was sponsored by the Canterbury Earthquake Recovery Authority (CERA) and consisted of two phases: The first was an analysis of existing information detailing the effects of hazardous natural events on Canterbury Lifeline Utilities in the past 15 years. The aim of this “Lessons Learned” project was to produce an analysis report that identified key themes from the research, gaps in the existing data and to provide recommendations from these “Lessons Learned.” The Second phase was the development of a practical “Disaster Mitigation Guideline” that outlined lessons in the field of Emergency Sanitation. This research would build upon the first stage and would draw from international reference to develop a guideline that has practical implementation possibilities throughout the world.
The article asks whether disasters that destroy life but leave the material infrastructure relatively intact tend to prompt communal coping focussing on loss, while disasters that destroy significant material infrastructure tend to prompt coping through restoration / re-building. After comparing memorials to New Zealand’s Christchurch earthquake and Pike River mine disasters, we outline circumstances in which collective restorative endeavour may be grassroots, organised from above, or manipulated, along with limits to effective restoration. We conclude that bereavement literature may need to take restoration more seriously, while disaster literature may need to take loss more seriously.
1. INTRODUCTION. Earthquakes and geohazards, such as liquefaction, landslides and rock falls, constitute a major risk for New Zealand communities and can have devastating impacts as the Canterbury 2010/2011 experience shows. Development patterns expose communities to an array of natural hazards, including tsunamis, floods, droughts, and sea level rise amongst others. Fostering community resilience is therefore vitally important. As the rhetoric of resilience is mainstreamed into the statutory framework, a major challenge emerges: how can New Zealand operationalize this complex and sometimes contested concept and build ‘community capitals’? This research seeks to provide insights to this question by critically evaluating how community capitals are conceptualized and how they can contribute to community resilience in the context of the Waimakariri District earthquake recovery and regeneration process.
The University of Canterbury CEISMIC Canterbury Earthquake Digital Archive draws on the example of the Centre for History and New Media’s (CHNM) September 11 Archive, which was used to collect digital artefacts after the bombing of the World Trade Centre buildings in 2001, but has gone significantly further than this project in its development as a federated digital archive. The new University of Canterbury Digital Humanities Programme – initiated to build the archive – has gathered together a Consortium of major national organizations to contribute content to a federated archive based on principles of openness and collaboration derived directly from the international digital humanities community.
Media law developments have continued across many areas in the period to mid-2013. In defamation, the New Zealand courts have begun to consider the issue of third party liability for publication on the internet, with cases involving Google searches and comments on a Facebook page. A parliamentary inquiry into a case that restricted parliamentary privilege has recommended a Parliamentary Privilege Act containing a definition of ‘proceedings in Parliament’. A satirical website increased its popularity when it fought off threatened defamation proceedings. In breach of confidence, a government body, the Earthquake Commission, obtained an interim injunction prohibiting publication of information accidentally released that dealt with the repair of earthquake-damaged properties in Christchurch, and a blogger made the information available online in breach of the order.
The Mw 6.2 February 22nd 2011 Christchurch earthquake (and others in the 2010-2011 Canterbury sequence) provided a unique opportunity to study the devastating effects of earthquakes first-hand and learn from them for future engineering applications. All major events in the Canterbury earthquake sequence caused widespread liquefaction throughout Christchurch’s eastern suburbs, particularly extensive and severe during the February 22nd event. Along large stretches of the Avon River banks (and to a lesser extent along the Heathcote) significant lateral spreading occurred, affecting bridges and the infrastructure they support. The first stage of this research involved conducting detailed field reconnaissance to document liquefaction and lateral spreading-induced damage to several case study bridges along the Avon River. The case study bridges cover a range of ages and construction types but all are reinforced concrete structures which have relatively short, stiff decks. These factors combined led to a characteristic deformation mechanism involving deck-pinning and abutment back-rotation with consequent damage to the abutment piles and slumping of the approaches. The second stage of the research involved using pseudo-static analysis, a simplified seismic modelling tool, to analyse two of the bridges. An advantage of pseudo-static analysis over more complicated modelling methods is that it uses conventional geotechnical data in its inputs, such as SPT blowcount and CPT cone resistance and local friction. Pseudo-static analysis can also be applied without excessive computational power or specialised knowledge, yet it has been shown to capture the basic mechanisms of pile behaviour. Single pile and whole bridge models were constructed for each bridge, and both cyclic and lateral spreading phases of loading were investigated. Parametric studies were carried out which varied the values of key parameters to identify their influence on pile response, and computed displacements and damages were compared with observations made in the field. It was shown that pseudo-static analysis was able to capture the characteristic damage mechanisms observed in the field, however the treatment of key parameters affecting pile response is of primary importance. Recommendations were made concerning the treatment of these governing parameters controlling pile response. In this way the future application of pseudo-static analysis as a tool for analysing and designing bridge pile foundations in liquefying and laterally spreading soils is enhanced.
The previously unknown Greendale Fault was buried beneath the Canterbury Plains and ruptured in the September 4th 2010 moment magnitude (Mw) 7.1 Darfield Earthquake. The Darfield Earthquake and subsequent Mw 6 or greater events that caused damage to Christchurch highlight the importance of unmapped faults near urban areas. This thesis examines the morphology, age and origin of the Canterbury Plains together with the paleoseismology and surface-rupture displacement distributions of the Greendale Fault. It offers new insights into the surface-rupture characteristics, paleoseismology and recurrence interval of the Greendale Fault and related structures involved in the 2010 Darfield Earthquake. To help constrain the timing of the penultimate event on the Greendale Fault the origin and age of the faulted glacial outwash deposits have been examined using sedimentological analysis of gravels and optically stimulated luminescence (OSL) dating combined with analysis of GPS and LiDAR survey data. OSL ages from this and other studies, and the analysis of surface paleochannel morphology and subsurface gravel deposits indicate distinct episodes of glacial outwash activity across the Canterbury Plains, at ~20 to 24 and ~28 to 33 kyr separated by a hiatus in sedimentation possibly indicating an interstadial period. These data suggest multiple glacial periods between ~18 and 35 kyr which may have occurred throughout the Canterbury region and wider New Zealand. A new model for the Waimakariri Fan is proposed where aggradation is mainly achieved during episodic sheet flooding with the primary river channel location remaining approximately fixed. The timing, recurrence interval and displacements of the penultimate surface-rupturing earthquake on the Greendale Fault have been constrained by trenching the scarp produced in 2010 at two locations. These excavations reveal a doubling of the magnitude of surface displacement at depths of 2-4 m. Aided by OSL ages of sand lenses in the gravel deposits, this factor-of-two increase is interpreted to indicate that in the central section of the Greendale Fault the penultimate surface-rupturing event occurred between ca. 20 and 30 kyr ago. The Greendale Fault remained undetected prior to the Darfield earthquake because the penultimate fault scarp was eroded and buried during Late Pleistocene alluvial activity. The Darfield earthquake rupture terminated against the Hororata Anticline Fault (HAF) in the west and resulted in up to 400 mm of uplift on the Hororata Anticline immediately above the HAF. Folding in 2010 is compared to Quaternary and younger deformation across the anticline recorded by a seismic reflection line, GPS-measured topographic profiles along fluvial surfaces, and river channel sinuosity and morphology. It is concluded that the HAF can rupture during earthquakes dissimilar to the 2010 event that may not be triggered by slip on the Greendale Fault. Like the Greendale Fault geomorphic analyses provide no evidence for rupture of the HAF in the last 18 kyr, with the average recurrence interval for the late Quaternary inferred to be at least ~10 kyr. Surface rupture of the Greendale Fault during the Darfield Earthquake produced one of the most accessible and best documented active fault displacement and geometry datasets in the world. Surface rupture fracture patterns and displacements along the fault were measured with high precision using real time kinematic (RTK) GPS, tape and compass, airborne light detection and ranging (LiDAR), and aerial photos. This allowed for detailed analysis of the cumulative strike-slip displacement across the fault zone, displacement gradient (ground shear strain) and the type of displacement (i.e. faulting or folding). These strain profiles confirm that the rupture zone is generally wide (~30 to ~300 metres) with >50% of displacement (often 70-80%) accommodated by ground flexure rather than discrete fault slip and ground cracking. The greatest fault-zone widths and highest proportions of folding are observed at fault stepovers.
Structural engineering is facing an extraordinarily challenging era. These challenges are driven by the increasing expectations of modern society to provide low-cost, architecturally appealing structures which can withstand large earthquakes. However, being able to avoid collapse in a large earthquake is no longer enough. A building must now be able to withstand a major seismic event with negligible damage so that it is immediately occupiable following such an event. As recent earthquakes have shown, the economic consequences of not achieving this level of performance are not acceptable. Technological solutions for low-damage structural systems are emerging. However, the goal of developing a low-damage building requires improving the performance of both the structural skeleton and the non-structural components. These non-structural components include items such as the claddings, partitions, ceilings and contents. Previous research has shown that damage to such items contributes a disproportionate amount to the overall economic losses in an earthquake. One such non-structural element that has a history of poor performance is the external cladding system, and this forms the focus of this research. Cladding systems are invariably complicated and provide a number of architectural functions. Therefore, it is important than when seeking to improve their seismic performance that these functions are not neglected. The seismic vulnerability of cladding systems are determined in this research through a desktop background study, literature review, and postearthquake reconnaissance survey of their performance in the 2010 – 2011 Canterbury earthquake sequence. This study identified that precast concrete claddings present a significant life-safety risk to pedestrians, and that the effect they have upon the primary structure is not well understood. The main objective of this research is consequently to better understand the performance of precast concrete cladding systems in earthquakes. This is achieved through an experimental campaign and numerical modelling of a range of precast concrete cladding systems. The experimental campaign consists of uni-directional, quasi static cyclic earthquake simulation on a test frame which represents a single-storey, single-bay portion of a reinforced concrete building. The test frame is clad with various precast concrete cladding panel configurations. A major focus is placed upon the influence the connection between the cladding panel and structural frame has upon seismic performance. A combination of experimental component testing, finite element modelling and analytical derivation is used to develop cladding models of the cladding systems investigated. The cyclic responses of the models are compared with the experimental data to evaluate their accuracy and validity. The comparison shows that the cladding models developed provide an excellent representation of real-world cladding behaviour. The cladding models are subsequently applied to a ten-storey case-study building. The expected seismic performance is examined with and without the cladding taken into consideration. The numerical analyses of the case-study building include modal analyses, nonlinear adaptive pushover analyses, and non-linear dynamic seismic response (time history) analyses to different levels of seismic hazard. The clad frame models are compared to the bare frame model to investigate the effect the cladding has upon the structural behaviour. Both the structural performance and cladding performance are also assessed using qualitative damage states. The results show a poor performance of precast concrete cladding systems is expected when traditional connection typologies are used. This result confirms the misalignment of structural and cladding damage observed in recent earthquake events. Consequently, this research explores the potential of an innovative cladding connection. The outcomes from this research shows that the innovative cladding connection proposed here is able to achieve low-damage performance whilst also being cost comparable to a traditional cladding connection. It is also theoretically possible that the connection can provide a positive value to the seismic performance of the structure by adding addition strength, stiffness and damping. Finally, the losses associated with both the traditional and innovative cladding systems are compared in terms of tangible outcomes, namely: repair costs, repair time and casualties. The results confirm that the use of innovative cladding technology can substantially reduce the overall losses that result from cladding damage.
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This thesis is about many things, not least of all the September 4th 2010 and February 22nd 2011 earthquakes that shook Christchurch, New Zealand. A city was shaken, events which worked to lay open the normally invisible yet vital objects, processes and technologies which are the focus of inquiry: the sewers, pipes, pumps, the digital technologies, the land and politics which constitute the Christchurch wastewater networks. The thesis is an eclectic mix drawing together methods and concepts from Bruno Latour, John Law, Giles Deleuze and Felix Guattari, Nigel Thrift, Donna Haraway and Patrick Joyce. It is an exploration of how the technologies and objects of sanitation perform the city, and how such things which are normally hidden and obscured, are made visible. The question of visibility is also turned toward the research itself: how does one observe, and describe? How are sociological visibilities constructed? Through the research, the encountering of objects in the field, the processes of method, the pedagogy of concepts, and the construction of risk, the thesis comes to be understood as a particular kind of social scientific artefact which assembles four different accounts: the first regards the construction of visibility; the second explores Christchurch city from the control room where the urban sanitary infrastructures are monitored; the third chapter looks at the formatted and embodied practices which emerge with the correlation of the city and sanitation; the fourth looks at the changing politics of a city grappling with severely damaged essential services, land and structures. The final chapter considers how the differences between romantic and baroque sensibilities mean that these four accounts elicit knowing not through smoothness or uniformity, but in partiality and non-coherence. This thesis is about pipes, pump stations, and treatment plants; about the effluent of a city; about the messiness of social science when confronted by the equally messy world of wastewater.
Christchurch earthquake events have raised questions on the adequacy of performance-based provisions in the current national building code. At present, in the building code the performance objectives are expressed in terms of safety and health criteria that could affect building occupants. In general, under the high intensity Christchurch events, buildings performed well in terms of life-safety (with a few exceptions) and it proved that the design practices adopted for those buildings could meet the performance objectives set by the building code. However, the damage incurred in those buildings resulted in unacceptably high economic loss. It is timely and necessary to revisit the objectives towards building performance in the building code and to include provisions for reducing economic implications in addition to the current requirements. Based on the observed performance of some buildings, a few specific issues in the current design practices that could have contributed to extensive damage have been identified and recommended for further research leading towards improved performance of structures. In particular, efforts towards innovative design/construction solutions with low-damage concepts are encouraged. New Zealand has been one of the leading countries in developing many innovative technologies. However, such technically advanced research findings usually face challenges towards implementation. Some of the reasons include: (i) lack of policy requirements; (iii) absence of demonstrated performance of new innovations to convince stakeholders; and (iv) non-existence of design guidelines. Such barriers significantly affect implementation of low damage construction and possible strategies to overcome those issues are discussed in this paper.
The capability of self-compacting concrete (SCC) in flowing through and filling in even the most congested areas makes it ideal for being used in congested reinforced concrete (RC) structural members such as beam-column joints (BCJ). However, members of tall multi-storey structures impose high capacity requirements where implementing normal-strength self-compacting concrete is not preferable. In the present study, a commercially reproducible high-strength self-compacting concrete (HSSCC), a conventionally vibrated high-strength concrete (CVHSC) and a normal strength conventionally vibrated concrete (CVC) were designed using locally available materials in Christchurch, New Zealand. Following the guidelines of the New Zealand concrete standards NZS3101, seven beam-column joints (BCJ) were designed. Factors such as the concrete type, grade of reinforcement, amount of joint shear stirrups, axial load, and direction of casting were considered variables. All BCJs were tested under a displacement-controlled quasi-static reversed cyclic regime. The cracking pattern at different load levels and the mode of failure were also recorded. In addition, the load, displacement, drift, ductility, joint shear deformations, and elongation of the plastic hinge zone were also measured during the experiment. It was found that not only none of the seismically important features were compromised by using HSSCC, but also the quality of material and ease of construction boosted the performance of the BCJs.
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.
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’.
A multi-disciplinary geo-structural-environmental engineering project funded by the Ministry of Business Innovation and Employment (MBIE) is being carried out at the University of Canterbury. The project aims at developing an eco-friendly seismic isolation foundation system which will improve the seismic performance of medium-density low-rise buildings. Such system is characterized by two main elements: 1) granulated scrap rubber mixed with gravelly soils to be placed beneath the structure, with the goal damping part of the seismic energy before it reaches the superstructure; and 2) a basement raft made of steel-fibre reinforced rubberised concrete (SFRRuC) to enhance the flexibility and toughness of the foundation, looking at better accommodating the displacement demand. In this paper, the main objectives, scope and methodology of the project will be briefly described. A literature review of the engineering properties of steel-fibre reinforced rubberised concrete (RuC) will be presented. Then, preliminary results on concrete mixes with different rubber and steel fibres content will be exhibited.
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.
