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Research papers, University of Canterbury Library

Recent advances in timber design at the University of Canterbury have led to new structural systems that are appropriate for a wide range of building types, including multi-storey commercial office structures. These buildings are competitive with more traditional construction materials in terms of cost, sustainability and structural performance. This paper provides seismic design recommendations and analytical modelling approaches, appropriate for the seismic design of post-tensioned coupled timber wall systems. The models are based on existing seismic design theory for precast post-tensioned concrete, modified to more accurately account for elastic deformation of the timber wall systems and the influence of the floor system. Experimental test data from a two storey post-tensioned timber building, designed, constructed and tested at the University of Canterbury is used to validate the analytical models.

Audio, Radio New Zealand

When Christchurch couple Maree Mockford and Bruce Vincent's home was badly damaged by the February earthquake they shifted into a caravan on their property. Six months later they're still roughing it, using a chemical toilet and showering off site.

Images, UC QuakeStudies

A photograph submitted by Jenny to the QuakeStories website. The description reads, "Hereford Street a couple of minutes after the quake. Dust from collapsed buildings visible in the background looking towards High Street.".

Images, Alexander Turnbull Library

A couple sits in a Travel Agency discussing places to go for a holiday. The travel agent says 'Worried about holidaying in New Zealand - well how about...' and she turns to the display of countries to visit on the wall behind her. Each of the countries is illustrated with a very negative image; e.g. 'Japan' with a nuclear symbol, 'Thailand' with a pile of human ashes, 'Sth Africa' with two arms raised in desperate supplication... Context - The couple do not want to visit New Zealand because of the Canterbury earthquakes and there seem to be an awful lot of natural disasters or wars or high expense etc. recently. Colour and black and white versions available Quantity: 2 digital cartoon(s).

Images, Alexander Turnbull Library

Text across the top of the cartoon reads 'You know you live in Christchurch when...' Six cameos follow reading 'You can stir a cup of coffee without a spoon' - a cup of coffee is shaken; 'after 30 years you finally know your neighbours' - a group of people get to know one another; 'the latest fitness craze is sandba' - a couple shovel a heap of liquefaction to music from their transistor; 'everyone gets to drive a slalom' - someone weaves along a road avoiding cracks and mud in their car; 'there's a craze in "unique garden features"' - a longdrop has been dug in the garden; and lastly 'you have tea under a doorframe' - a couple eats and drinks under a doorframe for safety. Context - the Christchurch earthquake of 22 February 2011. Published in The Press Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

A man representing 'EQC' (Earthquake Commission) talks to a couple outside their collapsed house. He says 'Unfortunately, this is a NORTH Canterbury collapse - so you'll only get your first $100,000 back.' Context: This refers both to the collapse of the South Canterbury Finance Company and to the problems that people are having with insurance companies in North Canterbury after the first Christchurch earthquake on September 4th 2010. Quantity: 1 digital cartoon(s).

Images, UC QuakeStudies

Army personnel beside the damaged Colombo Street Wesleyan Church. Danger tape has been stretched across Colombo Street to create a cordon. The photographer comments, "After the 22nd February earthquake, my wife and I spent one night in a tent outside our home and then left to stay with friends in Timaru for a couple of nights. On the way along Brougham Street, we passed the Sydenham Church on the corner of Colombo Street and Brougham Street. As you can see from the photos, the upper area has been extensively damaged. Most of the damage appears to be on the east facing wall although we didn't get much of a look at the other sides or, of course, the interior".

Images, UC QuakeStudies

Damage to the Colombo Street Wesleyan Church. The gable end has partially collapsed, and the window is damaged. The photographer comments, "After the 22nd February earthquake, my wife and I spent one night in a tent outside our home and then left to stay with friends in Timaru for a couple of nights. On the way along Brougham Street, we passed the Sydenham Church on the corner of Colombo Street and Brougham Street. As you can see from the photos, the upper area has been extensively damaged. Most of the damage appears to be on the east facing wall although we didn't get much of a look at the other sides or, of course, the interior".

Images, Alexander Turnbull Library

A couple are woken by loud thuds, rumbles and crashes. A woman leaps up in bed in a panic saying 'My God! Not another aftershock!' Her husband says 'Nah! Another flamin' haka!' A newspaper on the bed has a headline that reads 'World Cup in full swing.' Context: The World Cup began on Friday 9th September and ends on 23 October. People in Christchurch are still regularly jolted by aftershocks to the earthquakes of September 2010 and February and June 2011. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

An elderly couple sit having afternoon tea and chatting about Prince William's visit to Christchurch after the February 22 earthquake. The woman expresses delight that 'Prince William took time out to visit Christchurch' and her husband comments that there is 'Not much talk about becoming a republic lately'. Context - The Christchurch earthquakes of 4 September 2010 and 22 February 2011 and Prince William's subsequent visit. Also discussion about New Zealand's becoming a republic; there is a Republican Movement who are promoting the idea of an elected head of state. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

Text reads 'Collateral damage'. A couple stand looking at a broken column surrounded by fallen masonry; text on the column reads 'Curbs on govt spending'. The man says 'It's a shame. It was due to be unveiled in a few weeks'. Context - the Christchurch earthquake of 22 February 2011; curbs on government spending can be seen as 'collateral damage'. In December 2010 Finance Minister Bill English pledged to keep a cap on spending to rein in a widening deficit as slower consumer demand hinders the economic recovery and hurts tax receipts. The earthquake will make economic recovery even more difficult. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

Text across the top of the cartoon reads 'Greener pastures for red zone residents?... A new subdivision named 'Quakehaven' has streets named 'Wobble Way', 'Poopong Parade', 'Turd Tce.', 'Liquefaction Lane' etc. One of a couple visiting the new area says 'I've got a bad feeling about this new subdivision!' Context - Housing after the Christchurch earthquakes. After the first Land Report was delivered on 23rd June people whose houses were in the Red Zone had their properties bought up by the government and now have to move to new subdivisions. The suggestion in the cartoon is that the subdivisions may not be on safe ground. Quantity: 1 digital cartoon(s).

Images, UC QuakeStudies

Heavy traffic at the corner of Moorhouse Avenue and Manchester Street as people attempt to leave the city centre shortly after the 22 February earthquake. The photographer comments, "Just after the aftershock settled on Tuesday afternoon, myself and colleagues fled our Tuam Street office to absolute devastation outside. We couldn't see more than a block in either direction due to the clouds of dust that had arisen from buildings that had just collapsed ... From here, we picked up our vehicles from the CCC car park and headed out to get out of the chaos to a position where we could check on loved ones ... As we got to Moorhouse Avenue, we found we had to quickly drive underneath [the Colombo Street overbridge]and carry on down to Brougham Street as the bridge was being closed at that moment. From Brougham, we headed back up towards Madras. The traffic lights were out and the intersection was chaos. Over the next couple of hours, we continued crawling through heavy traffic. Impressively, everyone was very orderly despite the feeling of panic and the continuing aftershocks. We chatted to others in other vehicles to exchange news and stopped to speak to a lady that had broken down following water in the engine after having driven hrough floods".

Research papers, University of Canterbury Library

The NMIT Arts & Media Building is the first in a new generation of multistorey timber structures. It employs an advanced damage avoidance earthquake design that is a world first for a timber building. Aurecon structural engineers are the first to use this revolutionary Pres-Lam technology developed at the University of Canterbury. This technology marks a fundamental change in design philosophy. Conventional seismic design of multi-storey structures typically depends on member ductility and the acceptance of a certain amount of damage to beams, columns and walls. The NMIT seismic system relies on pairs of coupled LVL shear walls that incorporate high strength steel tendons post-tensioned through a central duct. The walls are centrally fixed allowing them to rock during a seismic event. A series of U-shaped steel plates placed between the walls form a coupling mechanism, and act as dissipators to absorb seismic energy. The design allows the primary structure to remain essentially undamaged while readily replaceable connections act as plastic fuses. In this era where sustainability is becoming a key focus, the extensive use of timber and engineered-wood products such as LVL make use of a natural resource all grown and manufactured within a 100km radius of Nelson. This project demonstrates that there are now cost effective, sustainable and innovative solutions for multi-story timber buildings with potential applications for building owners in seismic areas around the world.

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

Timber has experienced renewed interests as a sustainable building material in recent times. Although traditionally it has been the prime choice for residential construction in New Zealand and some other parts of the world, its use can be increased significantly in the future through a wider range of applications, particularly when adopting engineered wood material, Research has been started on the development of innovative solutions for multi-storey non-residential timber buildings in recent years and this study is part of that initiative. Application of timber in commercial and office spaces posed some challenges with requirements of large column-free spaces. The current construction practice with timber is not properly suited for structures with the aforementioned required characteristics and new type of structures has to be developed for this type of applications. Any new structural system has to have adequate capacity for carry the gravity and lateral loads due to occupancy and the environmental effects. Along with wind loading, one of the major sources of lateral loads is earthquakes. New Zealand, being located in a seismically active region, has significant risk of earthquake hazard specially in the central region of the country and any structure has be designed for the seismic loading appropriate for the locality. There have been some significant developments in precast concrete in terms of solutions for earthquake resistant structures in the last decade. The “Hybrid” concept combining post-tensioning and energy dissipating elements with structural members has been introduced in the late 1990s by the precast concrete industry to achieve moment-resistant connections based on dry jointed ductile connections. Recent research at the University of Canterbury has shown that the concept can be adopted for timber for similar applications. Hybrid timber frames using post-tensioned beams and dissipaters have the potential to allow longer spans and smaller cross sections than other forms of solid timber frames. Buildings with post-tensioned frames and walls can have larger column-free spaces which is a particular advantage for non-residential applications. While other researchers are focusing on whole structural systems, this research concentrated on the analysis and design of individual members and connections between members or between member and foundation. This thesis extends existing knowledge on the seismic behaviour and response of post-tensioned single walls, columns under uni-direction loads and small scale beam-column joint connections into the response and design of post-tensioned coupled walls, columns under bi-directional loading and full-scale beam-column joints, as well as to generate further insight into practical applications of the design concept for subassemblies. Extensive experimental investigation of walls, column and beam-column joints provided valuable confirmation of the satisfactory performance of these systems. In general, they all exhibited almost complete re-centering capacity and significant energy dissipation, without resulting into structural damage. The different configurations tested also demonstrated the flexibility in design and possibilities for applications in practical structures. Based on the experimental results, numerical models were developed and refined from previous literature in precast concrete jointed ductile connections to predict the behaviour of post-tensioned timber subassemblies. The calibrated models also suggest the values of relevant parameters for applications in further analysis and design. Section analyses involving those parameters are performed to develop procedures to calculate moment capacities of the subassemblies. The typical features and geometric configurations the different types of subassemblies are similar with the only major difference in the connection interfaces. With adoption of appropriate values representing the corresponding connection interface and incorporation of the details of geometry and configurations, moment capacities of all the subassemblies can be calculated with the same scheme. That is found to be true for both post-tensioned-only and hybrid specimens and also applied for both uni-directional and bi-directional loading. The common section analysis and moment capacity calculation procedure is applied in the general design approach for subassemblies.