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Research papers, University of Canterbury Library

We measure the longer-term effect of a major earthquake on the local economy, using night-time light intensity measured from space, and investigate whether insurance claim payments for damaged residential property affected the local recovery process. We focus on the destructive Canterbury Earthquake Sequence (CES) 2010 -2011 as our case study. Uniquely for this event, more than 95% of residential housing units were covered by insurance, but insurance payments were staggered over 5 years, enabling us to identify their local impact. We find that night-time luminosity can capture the process of recovery and describe the recovery’s determinants. We also find that insurance payments contributed significantly to the process of economic recovery after the earthquake, but delayed payments were less affective and cash settlement of claims were more effective than insurance-managed repairs in contributing to local recovery.

Images, UC QuakeStudies

Moira Fraser stands on a mound of liquefaction. The liquefaction is high enough that she is able to hold onto to the spouting of the house next to the mound. A broken fence can be seen protruding through the liquefaction. The property is on Waireka Lane in Bexley.

Images, UC QuakeStudies

A photograph submitted by Philip Broderick Willis to the QuakeStories website. The description reads, "Timaru Welfare Centre – Set up for EQ evacuees. Thought it was a little unfortunate that the only suitable venue there had a spring-loaded floor! Still, they were so welcoming and wonderful. It was such a relief to be there.".

Images, UC QuakeStudies

A close-up photograph of plastic bottles that were part of a temporary installation titled ING. ING was created by students from Unitec for CityUps - a 'city of the future for one night only', and the main event of FESTA 2014.

Images, UC QuakeStudies

A photograph of Speakers' Corner, an event that gathered citizens, architects, urbanists, developers and government officials to The Commons to speak about the importance of flexible and temporary spaces in the creation of cities. Speakers' Corner was part of FESTA 2014 and supported by Athfield Architects.

Images, UC QuakeStudies

A house in Christchurch with a red sticker on the window indicating that it is unsafe to enter. "No entry" and a large cross have also been spray painted on the front fence to warn people off. On the right side of the house, a tarpaulin can be seen covering a collapsed brick wall.

Images, UC QuakeStudies

A photograph of Mike Hewson's artwork, 'Government Life Suspension', on the side of the former Chancery Arcade. The photograph is taken from an angle such that the artwork appears to be a reflection of the Government Life building behind it.

Images, UC QuakeStudies

A photograph of Mike Hewson's artwork, 'Government Life Suspension', on the side of the former Chancery Arcade. The photograph is taken from an angle such that the artwork appears to be a reflection of the Government Life building behind it.

Images, UC QuakeStudies

A photograph of Mike Hewson's artwork, 'Deconstruction', on the walkway between Ballantyne's and the former bus exchange building. The photograph is taken from beneath the walkway, so that the distorted perspective which enables the illusion can be seen.

Images, UC QuakeStudies

Workers eat lunch at an outdoor table next to the Gap Filler Community Chess Set on Colombo Street. The Chess Set was a collaboration between Gap Filler and students at the University of Canterbury. The project aimed to restore the iconic Christchurch Chess Set that used to be played in Cathedral Square.

Images, UC QuakeStudies

A photograph of Speakers' Corner, an event that gathered citizens, architects, urbanists, developers and government officials to The Commons to speak about the importance of flexible and temporary spaces in the creation of cities. Speakers' Corner was part of FESTA 2014 and supported by Athfield Architects.

Images, UC QuakeStudies

A photograph of children standing on the plinth where the statue of John Robert Godley, Canterbury's founder, once stood. Members of the public are viewing the damaged cathedral from a walkway that was opened up between Re:Start Mall and Cathedral Square to allow temporary public access.

Images, UC QuakeStudies

A photograph of a detail of the front of Christ Church Cathedral. A stained-glass window remains intact despite the collapsed stonework that surrounds it. The upper part of the front wall has crumbled. Steel bracing has been placed against the wall to limit further damage.

Research papers, The University of Auckland Library

The influence of nonlinear soil-foundation-structure interaction (SFSI) on the performance of multi-storey buildings during earthquake events has become increasingly important in earthquake resistant design. For buildings on shallow foundations, SFSI refers to nonlinear geometric effects associated with uplift of the foundation from the supporting soil as well as nonlinear soil deformation effects. These effects can potentially be beneficial for structural performance, reducing forces transmitted from ground shaking to the structure. However, there is also the potential consequence of residual settlement and rotation of the foundation. This Thesis investigates the influence of SFSI in the performance of multi-storey buildings on shallow foundations through earthquake observations, experimental testing, and development of spring-bed numerical models that can be incorporated into integrated earthquake resistant design procedures. Observations were made following the 22 February 2011 Christchurch Earthquake in New Zealand of a number of multi-storey buildings on shallow foundations that performed satisfactorily. This was predominantly the case in areas where shallow foundations, typically large raft foundations, were founded on competent gravel and where there was no significant manifestation of liquefaction at the ground surface. The properties of these buildings and the soils they are founded on directed experimental work that was conducted to investigate the mechanisms by which SFSI may have influenced the behaviour of these types of structure-foundation systems. Centrifuge experiments were undertaken at the University of Dundee, Scotland using a range of structure-foundation models and a layer of dense cohesionless soil to simulate the situation in Christchurch where multi-storey buildings on shallow foundations performed well. Three equivalent single degree of freedom (SDOF) models representing 3, 5, and 7 storey buildings with identical large raft foundations were subjected to a range of dynamic Ricker wavelet excitations and Christchurch Earthquake records to investigate the influence of SFSI on the response of the equivalent buildings. The experimental results show that nonlinear SFSI has a significant influence on structural response and overall foundation deformations, even though the large raft foundations on competent soil meant that there was a significant reserve of bearing capacity available and nonlinear deformations may have been considered to have had minimal effect. Uplift of the foundation from the supporting soil was observed across a wide range of input motion amplitudes and was particularly significant as the amplitude of motion increased. Permanent soil deformation represented by foundation settlement and residual rotation was also observed but mainly for the larger input motions. However, the absolute extent of uplift and permanent soil deformation was very small compared to the size of the foundation meaning the serviceability of the building would still likely be maintained during large earthquake events. Even so, the small extent of SFSI resulted in attenuation of the response of the structure as the equivalent period of vibration was lengthened and the equivalent damping in the system increased. The experimental work undertaken was used to validate and enhance numerical modelling techniques that are simple yet sophisticated and promote interaction between geotechnical and structural specialists involved in the design of multi-storey buildings. Spring-bed modelling techniques were utilised as they provide a balance between ease of use, and thus ease of interaction with structural specialists who have these techniques readily available in practice, and theoretically rigorous solutions. Fixed base and elastic spring-bed models showed they were unable to capture the behaviour of the structure-foundation models tested in the centrifuge experiments. SFSI spring-bed models were able to more accurately capture the behaviour but recommendations were proposed for the parameters used to define the springs so that the numerical models closely matched experimental results. From the spring-bed modelling and results of centrifuge experiments, an equivalent linear design procedure was proposed along with a procedure and recommendations for the implementation of nonlinear SFSI spring-bed models in practice. The combination of earthquake observations, experimental testing, and simplified numerical analysis has shown how SFSI is influential in the earthquake performance of multi-storey buildings on shallow foundations and should be incorporated into earthquake resistant design of these structures.

Research papers, The University of Auckland Library

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.