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Images, eqnz.chch.2010

Column reinforcement exposed under spalled concrete after the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010.

Images, eqnz.chch.2010

Evacuating a central city flat which has been condemned following the magnitude 7.1 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

Column reinforcement exposed under spalled concrete after the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010.

Images, eqnz.chch.2010

Cordon at the Tuam Street - Madras Street intersection, following the magnitude 7.1 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

Column reinforcement exposed under spalled concrete after the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010.

Images, eqnz.chch.2010

Column reinforcement exposed under spalled concrete after the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010.

Images, eqnz.chch.2010

Column reinforcement exposed under spalled concrete after the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010.

Images, eqnz.chch.2010

Column reinforcement exposed under spalled concrete after the magnitude 7.1 earthquake that struck Christchurch on Saturday 4 September 2010.

Images, eqnz.chch.2010

Parapet and roof of this building collapsed during the magnitude 7.1 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

Parapet and roof of this building collapsed during the magnitude 7.1 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

This shop on Tuam Street survived rhe magnitude 7.1 earthquake that hit Christchurch on Saturday 4 September 2010.

Images, eqnz.chch.2010

Crack in the parapet of this building, resulting from the magnitude 7,1 earthquake that struck Christchurch on 4 September 2010.

Images, eqnz.chch.2010

Parapet and roof of this building collapsed during the magnitude 7.1 earthquake in Christchurch on Saturday 4-9-2010.

Research papers, The University of Auckland Library

Following the devastating 1931 Hawke's Bay earthquake, buildings in Napier and surrounding areas in the Hawke's Bay region were rebuilt in a comparatively homogenous structural and architectural style comprising the region's famous Art Deco stock. These interwar buildings are most often composed of reinforced concrete two-way space frames, and although they have comparatively ductile detailing for their date of construction, are often expected to be brittle, earthquake-prone buildings in preliminary seismic assessments. Furthermore, the likelihood of global collapse of an RC building during a design-level earthquake became an issue warranting particular attention following the collapse of multiple RC buildings in the February 22, 2011 Christchurch earthquake. Those who value the architectural heritage and future use of these iconic Art Deco buildings - including building owners, tenants, and city officials, among others - must consider how they can be best preserved and utilized functionally given the especially pressing implications of relevant safety, regulatory, and economic factors. This study was intended to provide information on the seismic hazard, geometric weaknesses, collapse hazards, material properties, structural detailing, empirically based vulnerability, and recommended analysis approaches particular to Art Deco buildings in Hawke's Bay as a resource for professional structural engineers tasked with seismic assessments and retrofit designs for these buildings. The observed satisfactory performance of similar low-rise, ostensibly brittle RC buildings in other earthquakes and the examination of the structural redundancy and expected column drift capacities in these buildings, led to the conclusion that the seismic capacity of these buildings is generally underrated in simple, force-based assessments.

Research papers, The University of Auckland Library

It is well known that buildings constructed using unreinforced masonry (URM) are susceptible to damage from earthquake induced lateral forces that may result in partial or full building collapse. The 2010/2011 Canterbury earthquakes are the most recent New Zealand example of destructive earthquakes, which have drawn people's attention to the inherent seismic weaknesses of URM buildings and anchored masonry veneer systems in New Zealand. A brief review of the data collected following the 2010 Darfield earthquake and more comprehensive documentation of data that was collected following the 2011 Christchurch earthquake is presented, along with the findings from subsequent data interrogation. Large stocks of earthquake prone vintage URM buildings that remain in New Zealand and in other seismically active parts of the world result in the need for minimally invasive and cost effective seismic retrofit techniques. The principal objective of the doctoral research reported herein was to investigate the applicability of near surface mounted (NSM) carbon fibre reinforced polymer (CFRP) strips as a seismic improvement technique. A comprehensive experimental program consisting of 53 pull tests is presented and is used to assess the accuracy of existing FRP-to-masonry bond models, with a modified model being proposed. The strength characteristics of vintage clay brick URM wall panels from two existing URM buildings was established and used as a benchmark when manufacturing replica clay brick test assemblages. The applicability of using NSM CFRP strips as a retrofitting technique for improving the shear strength and the ductility capacity of multi-leaf URM walls constructed using solid clay brick masonry is investigated by varying CFRP reinforcement ratios. Lastly, an experimental program was undertaken to validate the proposed design methodology for improving the strength capacity of URM walls. The program involved testing full-scale walls in a laboratory setting and testing full-scale walls in-situ in existing vintage URM buildings. Experimental test results illustrated that the NSM CFRP technique is an effective method to seismically strengthen URM buildings.

Research papers, University of Canterbury Library

This paper presents the ongoing development of a new 3D seismic velocity model of Canterbury, New Zealand. The model explicitly represents the Canterbury sedimentary basin, and other significant geologic horizons, which are expected to have important implications on observed ground motions. The model utilizes numerous sources of data, including 3D regional tomography with a variable-depth inferred Moho, seismic reflection survey lines, geotechnical boreholes and well logs, spectral analysis of surface waves, and CPT logs which provide velocity constraints over their respective ranges of application. The model provides P- and S-wave velocity and density (i.e. Vp, Vs and p) over a grid of input points, and is presently being utilized in broadband ground motion simulations of the 2010-2011 Canterbury earthquakes. Comparison of simulated ground motions with those observed in the 2010-2011 Canterbury earthquakes will help provide a better understanding of the salient physical processes which characterized the unique set of strong ground motions recorded in this sequence of earthquake events.

Research papers, University of Canterbury Library

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.

Research papers, University of Canterbury Library

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.

Videos, UC QuakeStudies

A video of the first part of a series of talks on the topic of Planning and People, at the 2012 Seismics and the City forum. The talks are as follows: Mary Devine, Managing Director of Ballantyne and Co, on Anchoring Re:START and holding the centre; Anthony Leighs, Chief Executive of Leighs Construction, on Deconstruction and Reconstruction; and Sam Johnson, founder of the Student Volunteer Army, on Mobilising a Quick Response.

Videos, UC QuakeStudies

A video of the second part of a series of talks on the topic of Planning and People, at the 2012 Seismics and the City forum. The talks are as follows: Mary Devine, Managing Director of Ballantyne and Co, on Anchoring Re:START and holding the centre; Anthony Leighs, Chief Executive of Leighs Construction, on Deconstruction and Reconstruction; and Sam Johnson, founder of the Student Volunteer Army, on Mobilising a Quick Response

Images, eqnz.chch.2010

I could have sworn the street lamposts were vertical on Friday 3 September 2010! Magnitude 7 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

I could have sworn the street lamposts were vertical on Friday 3 September 2010! Magnitude 7 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

I could have sworn the street lamposts were vertical on Friday 3 September 2010! Magnitude 7 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

Shop parapet toppled in the magnitude 7 earthquake in Christchurch on Saturday 4-9-2010. This building was condemned and demolished on 9 September 2010.

Images, eqnz.chch.2010

I could have sworn the street lamposts were vertical on Friday 3 September 2010! Magnitude 7 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

I could have sworn the street lamposts were vertical on Friday 3 September 2010! Magnitude 7 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

I could have sworn the street lamposts were vertical on Friday 3 September 2010! Magnitude 7 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

I could have sworn the street lamposts were vertical on Friday 3 September 2010! Magnitude 7 earthquake in Christchurch on Saturday 4-9-2010.

Images, eqnz.chch.2010

Rescue services out in full force at the Christchurch Arts Centre following the magnitude 7 earthquake in Christchurch on Saturday 4-9-2010.