Two days after the 22 February 2011 M6.3 earthquake in Christchurch, New Zealand, three of the authors conducted a transect of the central city, with the goal of deriving an estimate of building damage levels. Although smaller in magnitude than the M7.1 4 September 2010 Darfield earthquake, the ground accelerations, ground deformation and damage levels in Christchurch central city were more severe in February 2011, and the central city was closed down to the general public. Written and photographic notes of 295 buildings were taken, including construction type, damage level, and whether the building would likely need to be demolished. The results of the transect compared favourably to Civil Defence rapid assessments made over the following month. Now, more than one year and two major aftershocks after the February 2011 earthquake these initial estimates are compared to the current demolition status to provide an updated understanding of the state of central Christchurch.
The Screw Driving Sounding (SDS) method developed in Japan is a relatively new insitu testing technique to characterise soft shallow sites, typically those required for residential house construction. An SDS machine drills a rod into the ground in several loading steps while the rod is continuously rotated. Several parameters, such as torque, load and speed of penetration, are recorded at every rotation of the rod. The SDS method has been introduced in New Zealand, and the results of its application for characterising local sites are discussed in this study. A total of 164 SDS tests were conducted in Christchurch, Wellington and Auckland to validate/adjust the methodologies originally developed based on the Japanese practice. Most of the tests were conducted at sites where cone penetration tests (CPT), standard penetration tests (SPT) and borehole logs were available; the comparison of SDS results with existing information showed that the SDS method has great potential as an in-situ testing method for classifying the soils. By compiling the SDS data from 3 different cities and comparing them with the borehole logs, a soil classification chart was generated for identifying the soil type based on SDS parameters. Also, a correlation between fines content and SDS parameters was developed and a procedure for estimating angle of internal friction of sand using SDS parameters was investigated. Furthermore, a correlation was made between the tip resistance of the CPT and the SDS data for different percentages of fines content. The relationship between the SPT N value and a SDS parameter was also proposed. This thesis also presents a methodology for identifying the liquefiable layers of soil using SDS data. SDS tests were performed in both liquefied and non-liquefied areas in Christchurch to find a representative parameter and relationship for predicting the liquefaction potential of soil. Plots were drawn of the cyclic shear stress ratios (CSR) induced by the earthquakes and the corresponding energy of penetration during SDS tests. By identifying liquefied or unliquefied layers using three different popular CPT-based methods, boundary lines corresponding to the various probabilities of liquefaction happening were developed for different ranges of fines contents using logistic regression analysis, these could then be used for estimating the liquefaction potential of soil directly from the SDS data. Finally, the drilling process involved in screw driving sounding was simulated using Abaqus software. Analysis results proved that the model successfully captured the drilling process of the SDS machine in sand. In addition, a chart to predict peak friction angles of sandy sites based on measured SDS parameters for various vertical effective stresses was formulated. As a simple, fast and economical test, the SDS method can be a reliable alternative insitu test for soil and site characterisation, especially for residential house construction.
Utility managers are always looking for appropriate tools to estimate seismic damage in wastewater networks located in earthquake prone areas. Fragility curves, as an appropriate tool, are recommended for seismic vulnerability analysis of buried pipelines, including pressurised and unpressurised networks. Fragility curves are developed in pressurised networks mainly for water networks. Fragility curves are also recommended for seismic analysis in unpressurised networks. Applying fragility curves in unpressurised networks affects accuracy of seismic damage estimation. This study shows limitations of these curves in unpressurised networks. Multiple case study analysis was applied to demonstrate the limitations of the application of fragility curves in unpressurised networks in New Zealand. Four wastewater networks within New Zealand were selected as case studies and various fragility curves used for seismic damage estimation. Observed damage in unpressurised networks after the 2007 earthquake in Gisborne and the 2010 earthquake in Christchurch demonstrate the appropriateness of the applied fragility curves to New Zealand wastewater networks. This study shows that the application of fragility curves, which are developed from pressurised networks, cannot be accurately used for seismic damage assessment in unpressurised wastewater networks. This study demonstrated the effects of different parameters on seismic damage vulnerability of unpressurised networks.
In September 2010 and February 2011 the Canterbury region of New Zealand was struck by two powerful earthquakes, registering magnitude 7.1 and 6.3 respectively on the Richter scale. The second earthquake was centred 10 kilometres south-east of the centre of Christchurch (the region’s capital and New Zealand’s third most populous urban area, with approximately 360,000 residents) at a depth of five kilometres. 185 people were killed, making it the second deadliest natural disaster in New Zealand’s history. (66 people were killed in the collapse of one building alone, the six-storey Canterbury Television building.) The earthquake occurred during the lunch hour, increasing the number of people killed on footpaths and in buses and cars by falling debris. In addition to the loss of life, the earthquake caused catastrophic damage to both land and buildings in Christchurch, particularly in the central business district. Many commercial and residential buildings collapsed in the tremors; others were damaged through soil liquefaction and surface flooding. Over 1,000 buildings in the central business district were eventually demolished because of safety concerns, and an estimated 70,000 people had to leave the city after the earthquakes because their homes were uninhabitable. The New Zealand Government declared a state of national emergency, which stayed in force for ten weeks. In 2014 the Government estimated that the rebuild process would cost NZ$40 billion (approximately US$27.3 billion, a cost equivalent to 17% of New Zealand’s annual GDP). Economists now estimate it could take the New Zealand economy between 50 and 100 years to recover. The earthquakes generated tens of thousands of insurance claims, both against private home insurance companies and against the New Zealand Earthquake Commission, a government-owned statutory body which provides primary natural disaster insurance to residential property owners in New Zealand. These ranged from claims for hundreds of millions of dollars concerning the local port and university to much smaller claims in respect of the thousands of residential homes damaged. Many of these insurance claims resulted in civil proceedings, caused by disputes about policy cover, the extent of the damage and the cost and/or methodology of repairs, as well as failures in communication and delays caused by the overwhelming number of claims. Disputes were complicated by the fact that the Earthquake Commission provides primary insurance cover up to a monetary cap, with any additional costs to be met by the property owner’s private insurer. Litigation funders and non-lawyer claims advocates who took a percentage of any insurance proceeds also soon became involved. These two factors increased the number of parties involved in any given claim and introduced further obstacles to resolution. Resolving these disputes both efficiently and fairly was (and remains) central to the rebuild process. This created an unprecedented challenge for the justice system in Christchurch (and New Zealand), exacerbated by the fact that the Christchurch High Court building was itself damaged in the earthquakes, with the Court having to relocate to temporary premises. (The High Court hears civil claims exceeding NZ$200,000 in value (approximately US$140,000) or those involving particularly complex issues. Most of the claims fell into this category.) This paper will examine the response of the Christchurch High Court to this extraordinary situation as a case study in innovative judging practices and from a jurisprudential perspective. In 2011, following the earthquakes, the High Court made a commitment that earthquake-related civil claims would be dealt with as swiftly as the Court's resources permitted. In May 2012, it commenced a special “Earthquake List” to manage these cases. The list (which is ongoing) seeks to streamline the trial process, resolve quickly claims with precedent value or involving acute personal hardship or large numbers of people, facilitate settlement and generally work proactively and innovatively with local lawyers, technical experts and other stakeholders. For example, the Court maintains a public list (in spreadsheet format, available online) with details of all active cases before the Court, listing the parties and their lawyers, summarising the facts and identifying the legal issues raised. It identifies cases in which issues of general importance have been or will be decided, with the expressed purpose being to assist earthquake litigants and those contemplating litigation and to facilitate communication among parties and lawyers. This paper will posit the Earthquake List as an attempt to implement innovative judging techniques to provide efficient yet just legal processes, and which can be examined from a variety of jurisprudential perspectives. One of these is as a case study in the well-established debate about the dialogic relationship between public decisions and private settlement in the rule of law. Drawing on the work of scholars such as Hazel Genn, Owen Fiss, David Luban, Carrie Menkel-Meadow and Judith Resnik, it will explore the tension between the need to develop the law through the doctrine of precedent and the need to resolve civil disputes fairly, affordably and expeditiously. It will also be informed by the presenter’s personal experience of the interplay between reported decisions and private settlement in post-earthquake Christchurch through her work mediating insurance disputes. From a methodological perspective, this research project itself gives rise to issues suitable for discussion at the Law and Society Annual Meeting. These include the challenges in empirical study of judges, working with data collected by the courts and statistical analysis of the legal process in reference to settlement. September 2015 marked the five-year anniversary of the first Christchurch earthquake. There remains widespread dissatisfaction amongst Christchurch residents with the ongoing delays in resolving claims, particularly insurers, and the rebuild process. There will continue to be challenges in Christchurch for years to come, both from as-yet unresolved claims but also because of the possibility of a new wave of claims arising from poor quality repairs. Thus, a final purpose of presenting this paper at the 2016 Meeting is to gain the benefit of other scholarly perspectives and experiences of innovative judging best practice, with a view to strengthening and improving the judicial processes in Christchurch. This Annual Meeting of the Law and Society Association in New Orleans is a particularly appropriate forum for this paper, given the recent ten year anniversary of Hurricane Katrina and the plenary session theme of “Natural and Unnatural Disasters – human crises and law’s response.” The presenter has a personal connection with this theme, as she was a Fulbright scholar from New Zealand at New York University in 2005/2006 and participated in the student volunteer cleanup effort in New Orleans following Katrina. http://www.lawandsociety.org/NewOrleans2016/docs/2016_Program.pdf
Reinforced concrete (RC) frame buildings designed according to modern design standards achieved life-safety objectives during the Canterbury earthquakes in 2010-11 and the Kaikōura earthquake in 2016. These buildings formed ductile plastic hinges as intended and partial or total building collapse was prevented. However, despite the fact that the damage level of these buildings was relatively low to moderate, over 60% of multi-storey RC buildings in the Christchurch central business district were demolished due to insufficient insurance coverage and significant uncertainty in the residual capacity and repairability of those buildings. This observation emphasized an imperative need to improve understanding in evaluating the post-earthquake performance of earthquake-damaged buildings and to develop relevant post-earthquake assessment guidelines. This thesis focuses on improving the understanding of the residual capacity and repairability of RC frame buildings. A large-scale five-storey RC moment-resisting frame building was tested to investigate the behaviour of earthquake-damaged and repaired buildings. The original test building was tested with four ground motions, including two repeated design-level ground motions. Subsequently, the test building was repaired using epoxy injection and mortar patching and re-tested with three ground motions. The test building was assessed using key concepts of the ATC-145 post-earthquake assessment guideline to validate its assessment procedures and highlight potential limitations. Numerical models were developed to simulate the peak storey drift demand and identify damage locations. Additionally, fatigue assessment of steel reinforcement was conducted using methodologies as per ATC-145. The residual capacity of earthquake-strained steel reinforcement was experimentally investigated in terms of the residual fatigue capacity and the residual ultimate strain capacity. In addition to studying the fatigue capacity of steel reinforcement, the fatigue damage demand was estimated using 972 ground motion records. The deformation limit of RC beams and columns for damage control was explored to achieve a low likelihood of requiring performance-critical repair. A frame component test database was developed, and the deformation capacity at the initiation of lateral strength loss was examined in terms of the chord rotation, plastic rotation and curvature ductility capacity. Furthermore, the proposed curvature ductility capacity was discussed with the current design curvature ductility limits as per NZS 3101:2006.
Reinforced concrete buildings that satisfied modern seismic design criteria generally behaved as expected during the recent Canterbury and Kaikoura earthquakes in New Zealand, forming plastic hinges in intended locations. While this meant that life-safety performance objectives were met, widespread demolition and heavy economic losses took place in the aftermath of the earthquakes.The Christchurch central business district was particularly hard hit, with over 60% of the multistorey reinforced concrete buildings being demolished. A lack of knowledge on the post-earthquake residual capacity of reinforced concrete buildings was a contributing factor to the mass demolition.Many aspects related to the assessment of earthquake-damaged reinforced concrete buildings require further research. This thesis focusses on improving the state of knowledge on the post earthquakeresidual capacity and reparability of moderately damaged plastic hinges, with an emphasis on plastic hinges typical of modern moment frame structures. The repair method focussed on is epoxy injection of cracks and patching of spalled concrete. A targeted test program on seventeen nominally identical large-scale ductile reinforced concrete beams, three of which were repaired by epoxy injection following initial damaging loadings, was conducted to support these objectives. Test variables included the loading protocol, the loading rate, and the level of restraint to axial elongation.The information that can be gleaned from post-earthquake damage surveys is investigated. It is shown that residual crack widths are dependent on residual deformations, and are not necessarily indicative of the maximum rotation demands or the plastic hinge residual capacity. The implications of various other types of damage typical of beam and column plastic hinges are also discussed.Experimental data are used to demonstrate that the strength and deformation capacity of plastic hinges with modern seismic detailing are often unreduced as a result of moderate earthquake induced damage, albeit with certain exceptions. Special attention is given to the effects of prior yielding of the longitudinal reinforcement, accounting for the low-cycle fatigue and strain ageing phenomena. A material-level testing program on the low-cycle fatigue behaviour of grade 300E reinforcing steel was conducted to supplement the data available in the literature.A reduction in stiffness, relative to the initial secant stiffness to yield, occurs due to moderate plastic hinging damage. This reduction in stiffness is shown to be correlated with the ductility demand,and a proposed model gives a conservative lower-bound estimate of the residual stiffness following an arbitrary earthquake-type loading. Repair by epoxy injection is shown to be effective in restoring the majority of stiffness to plastic hinges in beams. Epoxy injection is also shown to have implications for the residual strength and elongation characteristics of repaired plastic hinges.
