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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

Currently there is a worldwide renaissance in timber building design. At the University of Canterbury, new structural systems for commercial multistorey timber buildings have been under development since 2005. These systems incorporate large timber sections connected by high strength post-tensioning tendons, and timber-concrete composite floor systems, and aim to compete with existing structural systems in terms of cost, constructability, operational and seismic performance. The development of post-tensioned timber systems has created a need for improved lateral force design approaches for timber buildings. Current code provisions for seismic design are based on the strength of the structure, and do not adequately account for its deformation. Because timber buildings are often governed by deflection, rather than strength, this can lead to the exceedence of design displacement limitations imposed by New Zealand codes. Therefore, accurate modeling approaches which define both the strength and deformation of post-tensioned timber buildings are required. Furthermore, experimental testing is required to verify the accuracy of these models. This thesis focuses on the development and experimental verification of modeling approaches for the lateral force design of post-tensioned timber frame and wall buildings. The experimentation consisted of uni-direcitonal and bi-directional quasi-static earthquake simulation on a two-thirds scale, two-storey post-tensioned timber frame and wall building with timber-concrete composite floors. The building was subjected to lateral drifts of up to 3% and demonstrated excellent seismic performance, exhibiting little damage. The building was instrumented and analyzed, providing data for the calibration of analytical and numerical models. Analytical and numerical models were developed for frame, wall and floor systems that account for significant deformation components. The models predicted the strength of the structural systems for a given design performance level. The static responses predicted by the models were compared with both experimental data and finite element models to evaluate their accuracy. The frame, wall and floor models were then incorporated into an existing lateral force design procedure known as displacement-based design and used to design several frame and wall structural systems. Predictions of key engineering demand parameters, such as displacement, drift, interstorey shear, interstorey moment and floor accelerations, were compared with the results of dynamic time-history analysis. It was concluded that the numerical and analytical models, presented in this thesis, are a sound basis for determining the lateral response of post-tensioned timber buildings. However, future research is required to further verify and improve these prediction models.

Research papers, University of Canterbury Library

An as-built reinforced concrete (RC) frame building designed and constructed according to pre-1970s code design construction practice has been recently tested on the shake table at the University of Canterbury. The specimen, 1/2.5 scaled version of the original prototype, consists of two 3-storey 2-bay asymmetric frames in parallel, one interior and one exterior, jointed together by transverse beams and floor slabs. Following the benchmark test, a retrofit intervention has been proposed to rehabilitate the tested specimen. In this paper, detailed information on the assessment and design of the seismic retrofit procedure using GFRP (glass fibre reinforced polymer) materials is given for the whole frame. Hierarchy of strength and sequence of events (damage mechanisms) in the panel zone region are evaluated using a moment-axial load (M-N) interaction performance domain, according to a performance-based retrofit philosophy. Specific limit states or design objectives are targeted with attention given to both strength and deformation limits. In addition, an innovative retrofit solution using FRP anchor dowels for the corner beam-column joints with slabs is proposed. Finally, in order to provide a practical tool for engineering practice, the retrofit procedure is provided in a step-by step flowchart fashion.

Research papers, University of Canterbury Library

Extended Direct Analysis (EDA), developed at the University of Canterbury, is an advance on the AISC Direct Analysis method for the analysis of frames subjected to static forces. EDA provides a faster, simple and more rational way to properly consider the second-order effects, initial residual stresses (IRS) and the initial imperfections or steel structures under one directional loading than conventional analysis methods. This research applied the EDA method to quantify the effect of member overstrength on frame behaviour for a single storey frame. Also, the effects of IRS, which were included in the EDA static analysis, but which are not considered explicitly in non-linear seismic analysis, were evaluated in two ways. Firstly, they were considered for simple structures subject to increasing cyclic displacement in different directions. Secondly, incremental dynamic analysis with realistic ground motion was used to quantify the likely effect of IRS in earthquakes. It was found that, contrary to traditional wisdom and practice, greater member strengths can result in lower frame strengths for frames under monotonic lateral loading. The structural lateral capacity of the overstrength case was reduced by 6% compared to the case using the dependable member strengths. Also, it resulted significantly different in member demands. Therefore, it is recommended that when either plastic analysis or EDA is used, that both upper and lower bounds on the likely member strength should be considered to determine the total frame strength and the member demands. Results of push-pull analysis under displacement control showed that for IRS ratio, gamma < 0.5 and axial compressive force ratio, N*/Ns, up to 0.5, IRS did affect the structural behaviour in the first half cycle. However, the behavior in the later cycles was not significantly affected. It also showed that the effect of initial residual stresses in the frame was less significant than for the column alone when the column was subjected to similar axial compressive force. The incremental dynamic analysis results from both cantilever column and the three-storey steel frame showed that by increasing gamma = 0 to 0.5, the effect of IRS on seismic responses, based on the 50% confidence level, was less than 3% for N*/Ns, up to 0.5.

Images, Alexander Turnbull Library

In three small frames above the main frame, milk tankers are shown bumping wildly over Christchurch roads made uneven by the earthquakes of September 4 2010 and February 22 2011; and in the large frame below a man is painting out the word 'milk' on a tanker and replacing it with the word 'butter'. Context - the bad roads caused by the erathquakes in Canterbury have turned the milk into butter. Colour and black and white versions available Title from file name Quantity: 2 digital cartoon(s).

Images, UC QuakeStudies

A view down Victoria Street from the corner of Victoria Street and Bealey Avenue. On the left is the damaged Knox Church, where the brick has crumbled but the wooden roof frame is still intact. In front is a tent where the Army is guarding the cordon from.

Images, UC QuakeStudies

A photograph of an Urban Search and Rescue team member removing a framed picture from the wall of a flat on Poplar Street during the Residential Access Project. The project gave residents temporary access within the red-zone cordon in order to retrieve items from their homes.

Images, UC QuakeStudies

A view down Victoria Street from the corner of Victoria Street and Bealey Avenue. On the left is the damaged Knox Church, where the brick has crumbled but the wooden roof frame is still intact. Behind is the the BDO building and on the left is an empty demolition site.

Images, Alexander Turnbull Library

In the first frame is an 'Emergency kit for national disaster' which is a bin full of disaster supplies like canned food, torch etc. In the second frame there is an 'Emergency kit for economic disaster...' - a bin containing a 'One way ticket to OZ'. Context - The national distaster kit is very relevant after the two earthquakes and numerous aftershocks in Christchurch and increasingly people are moving to Australia in search of jobs and opportunities that seem scarce in New Zealand. Quantity: 1 digital cartoon(s).

Images, eqnz.chch.2010

Picture Framing Gallery, Ferry Rd (28.02.2011) Woolston Christchurch Canterbury New Zealand © 2011 Phil Le Cren Photo Taken With: Canon EOS 1000D + Canon EF/EF-S lenses + 10.1 effective megapixels + 2.5-inch TFT color LCD monitor + Eye-level pentamirror SLR + Live View shooting. + EOS Built-in Sensor cleaning system...

Images, Alexander Turnbull Library

Text top left reads 'A tale of two quakes' In the first frame a man runs from 'radiation leaks' yelling 'The end of the world!' and in the second frame a man runs from the notion 'No World Cup?' yelling 'The end of the world!' Context - the terrible earthquake and tsunami in Japan 11 March 2011 that have led to the overheating of several nuclear power plants that are leaking radiation and threaten a nuclear catastrophe and the Christchurch earthquakes of 4 September 2010 and 22 February 2011 that have led to the decision that because of the amount of damage to the venue plus infrastructures and accommodation for visitors the Rugby World Cup will not be played in Christchurch. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

In the top frame a man reads a newspaper report that says 'Govt to buy up red stickered homes' and shouts 'That's it - I'm out!' His mate comments that he thought it was his neighbour's house that was munted and that his house was ok. In the lower frame the first man says 'That's right... and I don't want to live next door to a politician?!' Context - A report released 23 June 2011 has divided quake-hit Canterbury into four zones with those in the worst affected residential red zone offered cash to move out. The man in the cartoon thinks that the government is buying up the houses so that politicians can live in them. Colour and black and white versions available Quantity: 2 digital cartoon(s).

Images, eqnz.chch.2010

Picture Framing Gallery, Ferry Rd (23.02.2011) Woolston Christchurch Canterbury New Zealand © 2011 Phil Le Cren Photo Taken With: Canon EOS 1000D + Canon EF/EF-S lenses + 10.1 effective megapixels + 2.5-inch TFT color LCD monitor + Eye-level pentamirror SLR + Live View shooting. + EOS Built-in Sensor cleaning system...

Images, eqnz.chch.2010

Picture Framing Gallery, Ferry Rd (23.02.2011) Woolston Christchurch Canterbury New Zealand © 2011 Phil Le Cren Photo Taken With: Canon EOS 1000D + Canon EF/EF-S lenses + 10.1 effective megapixels + 2.5-inch TFT color LCD monitor + Eye-level pentamirror SLR + Live View shooting. + EOS Built-in Sensor cleaning system...

Images, eqnz.chch.2010

Picture Framing Gallery, Ferry Rd (23.02.2011) Woolston Christchurch Canterbury New Zealand © 2011 Phil Le Cren Photo Taken With: Canon EOS 1000D + Canon EF/EF-S lenses + 10.1 effective megapixels + 2.5-inch TFT color LCD monitor + Eye-level pentamirror SLR + Live View shooting. + EOS Built-in Sensor cleaning system...

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

A stack of wooden frames with the words "Quake makes world headlines" written on the uppermost frame. The photographer comments, "This is a sculpture at the CPIT facility in Christchurch. It is a series of squares placed over a column with writing on the squares. It is an excellent movable sculpture that conveys the Christchurch earthquake very well. The squares are placed so that they can slide over each other and even fall inside the other on one side. It is a pity that only two sides of the squares are written on".

Images, Alexander Turnbull Library

In the top frame someone unseen (Murray McCully) in the Beehive says 'John! - There's been a bad reaction to us taking special powers to fix problems in Auckland!' Prime Minister John Key says 'What Murray?' In the lower frame Minister for the Rugby World Cup, Murray McCully, says 'The worst hit parts of Christchurch have declared themselves Fan Zones!' and the PM says 'Oh S..t!' The little Evans man says 'Sounds better than Red Zone!' Context: Refers to the chaos over transport and crowd control in the fanzone when much larger numbers of people flocked to the Rugby World Cup opening and revelry than expected. The government used special powers to take over the management of Queens Wharf fanzone spaces previously managed by an Auckland Council group, thus rather undermining the Mayor, Len Brown and the Auckland City Council. A new plan was signed off under special powers by Murray McCully directly after the fiasco. The Christchurch comment refers to the areas worst hit by the earhquakes. Colour and black and white versions available Quantity: 2 digital cartoon(s).

Images, Alexander Turnbull Library

The upper of two frames shows Auckland all lit up for the Rugby World Cup and the lower frame shows Christchurch with a backdrop of munted buildings and a few people creating light with candles and torches. Context: The cartoon shows a contrast between the two cities as Christchurch struggles with the aftermath of the earthquakes and Auckland revels in the Rugby World Cup festivities. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

In the top frames two children shout 'four point one', 'three point six', and 'five point two' and in the frame below it is seen that they are responding to bumps in the road as their mother drives through Christchurch streets. Context - The children have become expert at guessing the seismic intensity of earthquakes in Christchurch and are now applying them to bumps in the road. Colour and black and white versions available Quantity: 2 digital cartoon(s).

Images, Alexander Turnbull Library

The text 'Rugby World Cup' runs across the top of the cartoon. Below is a poster depicting the shape of a rugby ball with a double koru design and the year '2011'. It is accompanied by the words 'Rugby New Zealand (well not quite all New Zealand)' Someone off screen kicks a rugby ball that represents 'Christrch' across the frame. Context - Christchurch has been told that they will not be able to host any Rugby World Cup games because of the damage to the city after the earthquakes 4 September 2010 and 22 February 2011. Quantity: 1 digital cartoon(s).