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Images, UC QuakeStudies

A motion-blurred photograph of houses, with the Port Hills in the background. The photographer comments, "This I hope gives you a feel of what it feels like in an earthquake. When you spend your whole life thinking that you and your home are built on solid ground, it can be quite a shock when you find it is not. You can feel the house shaking like a dog with a toy, rising up violently underneath you or the most gentle form which is when the ground moves gently like a wave moving under a rowing boat. It is not just the movement, you often get a rumbling sound which can precede a violent shake or can result in no movement at all. This means that some vehicles can sound like the rumbling initially and in the early days would get your heart racing. Another form of stress is when big excavators as heavy as a tank move as you can feel the ground shake from streets away, but you do not always hear the engine. For most of us the problem when the shaking starts, is wondering if this is the start of an extremely violent earthquake or will it peter out".

Images, UC QuakeStudies

Digitally manipulated image of the damaged Cathedral of the Blessed Sacrament, superimposed with a seismograph trace. The photographer comments, "What we want to forget, but must remember".

Images, UC QuakeStudies

A vehicle parked beside a broken streetlight in Parklands. The photographer comments, "This street light was shaken apart during the one of the double earthquakes on 23 December".

Research papers, University of Canterbury Library

An extensive research program is on-going at the University of Canterbury, New Zealand to develop new technologies to permit the construction of multi-storey timber buildings in earthquake prone areas. The system combines engineered timber beams, columns and walls with ductile moment resisting connections using post-tensioned tendons and eventually energy dissipaters. The extensive experimental testing on post-tensioned timber building systems has proved a remarkable lateral response of the proposed solutions. A wide number of post-tensioned timber subassemblies, including beam-column connections, single or coupled walls and column-foundation connections, have been analysed in static or quasi-static tests. This contribution presents the results of the first dynamic tests carried out with a shake-table. Model frame buildings (3-storey and 5-storey) on one-quarter scale were tested on the shake-table to quantify the response of post-tensioned timber frames during real-time earthquake loading. Equivalent viscous damping values were computed for post-tensioned timber frames in order to properly predict their response using numerical models. The dynamic tests were then complemented with quasi-static push and pull tests performed to a 3-storey post-tensioned timber frame. Numerical models were included to compare empirical estimations versus dynamic and quasi-static experimental results. Different techniques to model the dynamic behaviour of post-tensioned timber frames were explored. A sensitivity analysis of alternative damping models and an examination of the influence of designer choices for the post-tensioning force and utilization of column armouring were made. The design procedure for post-tensioned timber frames was summarized and it was applied to two examples. Inter-storey drift, base shear and overturning moments were compared between numerical modelling and predicted/targeted design values.

Research papers, University of Canterbury Library

In order to provide information related to seismic vulnerability of non-ductile reinforced concrete (RC) frame buildings, and as a complementary investigation on innovative feasible retrofit solutions developed in the past six years at the University of Canterbury on pre-19170 reinforced concrete buildings, a frame building representative of older construction practice was tested on the shake table. The specimen, 1/2.5 scale, consists of two 3-storey 2-bay asymmetric frames in parallel, one interior and one exterior, jointed together by transverse beams and floor slabs. The as-built (benchmark) specimen was first tested under increasing ground motion amplitudes using records from Loma Prieta Earthquake (California, 1989) and suffered significant damage at the upper floor, most of it due to lap splices failure. As a consequence, in a second stage, the specimen was repaired and modified by removing the concrete in the lap splice region, welding the column longitudinal bars, replacing the removed concrete with structural mortar, and injecting cracks with epoxy resin. The modified as-built specimen was then tested using data recorded during Darfield (New Zealand, 2010) and Maule (Chile, 2010) Earthquakes, with whom the specimen showed remarkably different responses attributed to the main variation in frequency content and duration. In this contribution, the seismic performance of the three series of experiments are presented and compared.

Images, UC QuakeStudies

Liquefaction silt. The photographer comments, "After the earthquake in Christchurch New Zealand, liquefaction covered the streets, but after it had risen from below ground whilst the ground was shaking it the liquid in the liquefaction wanted to drain away".