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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, University of Canterbury Library

This paper describes the performance of (or damage to) ceilings in buildings during the 22nd February 2011 Christchurch earthquake and the subsequent aftershocks. In buildings that suffered severe structural damage, ceilings and other non-structural components (rather expectedly) failed, but even in buildings with little damage to their structural systems, ceilings were found to be severely damaged. The extent of ceiling damage, where the ceilings were subject to severe shaking, depended on the type of the ceiling system, the size and weight of the ceilings and the interaction of ceilings with other elements. The varieties and extent of observed ceiling damage are discussed in this paper with the help of photographs taken after the earthquake.

Images, UC QuakeStudies

People gather at the corner of Colombo and St Asaph Streets shortly after the 22 February earthquake. A building has collapsed, and bricks and rubble litter the street. 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. Heading first along Manchester Street, buildings that were already heavily damaged were now completely written off. We couldn't get much further down Manchester Street so eventually made it to Colombo Street".

Images, UC QuakeStudies

A digitally manipulated image of the Gap Filler Monopoly board square on Manchester Street. The photographer comments, "On the site of a demolished earthquake damaged building in Christchurch, New Zealand is a Monopoly game square for giants. The Gap Filler Project makes the bare land where once a building once stood into something both interesting and unique and this time they created a massive Monopoly board square. In the game of Monopoly you move your player with a dog, shoe or maybe the hat, but as the most common thing in the City are diggers they have the placed one on the square. There are also two houses on Manchester Street, which is priced at $240".

Images, Alexander Turnbull Library

A chimpanzee paints with a palette of colours. Context: After the earthquakes in Christchurch buildings and areas were designated green, blue, red or white depending on the degree of damage. Buildings in the 'red' zone were then examined to ascertain whether they should be demolished or restored and sometimes the land itself was deemed unsafe. There have been many controversial decisions made which is the point the cartoon makes. Quantity: 1 digital cartoon(s).

Images, UC QuakeStudies

The Cranmer Court building, on the corner of Kilmore and Montreal Streets, after the 22 February 2011 earthquake. Large pieces of the building have collapsed, including the octagonal corner section that housed Plato Creative from March 2008 to November 2009. Masonry has fallen onto the footpath and road, and the site has been enclosed in a safety fence to keep people away. The whitewashed interior walls of one of the apartments can be seen.

Images, UC QuakeStudies

The damaged Cranmer Centre on the corner of Montreal and Armagh Streets shortly after the 22 February 2011 earthquake. The east wall of the building has crumbled onto the street and a man in a hard hat and high-visibility vest is directing people around it. There is scaffolding on the south side of the building from repair works after the 4 September 2010 earthquake. The gable in the background has also collapsed.

Images, UC QuakeStudies

A photograph of members of the Wellington Emergency Management Office Emergency Response Team examining an earthquake-damaged building on Acton Street. The closest section of the outer wall has collapsed, and the bricks and other rubble have fallen onto the pavement in front. A boat which was being stored inside has toppled over and is now sticking out of the building.

Images, UC QuakeStudies

A view across Wakefield Avenue in Sumner to several local businesses, including Sumner Asian Restaurant, KB's Bakery, Harcourt's and The Ruptured Duck Pizzeria and Bar. Metal pipes can be seen bracing the balcony and walls of the building housing Harcourt's and The Ruptured Duck. The building has been cordoned off by a safety fence, and large cracks are visible in its walls and cornice.

Audio, Radio New Zealand

Christchurch artist Mike Beer creates miniature models of Christchurch buildings that were lost in the Canterbury earthquakes. Through these tiny models Mike hopes to remind people of the buildings that once shaped the city - and bring back the feelings and memories associated with them. Mike, who goes by the name Ghostcat, says It's all about the connections people have with a time, and place. His models are to be displayed at Fiksate Gallery in Christchuch from April 9.

Images, UC QuakeStudies

A photograph of members of the Wellington Emergency Management Office Emergency Response Team examining an earthquake-damaged building on Acton Street. The closest section of the outer wall has collapsed, and the bricks and other rubble have fallen onto the pavement in front. A boat which was being stored inside has toppled over and is now sticking out of the building.

Images, UC QuakeStudies

The north-west end of the Arts Centre on the corner of Rolleston Avenue and Worcester Boulevard. The tip of the gable is missing as well as the spire which has been removed and braced on the footpath to limit damage. Wire fencing and road cones have been placed around the building as a cordon. In the distance, a crane is working on the building.

Audio, Radio New Zealand

A Christchurch woman whose mother died in the 2011 earthquake says an apology from the Christchurch mayor Lianne Dalziel does not lessen her grief. Yesterday - nine years and one day since the quake killed 185 people - Dalziel invited their families for a private apology. She acknowledged errors made by engineers and the city council in regards to the CTV building. Julie Hibbs lost her mother in the collapse of the building. She speaks to Susie Ferguson.

Research papers, University of Canterbury Library

Christchurch and Canterbury suffered significant housing losses due to the earthquakes. Estimates from the Earthquake Commission (EQC) (2011) suggest that over 150,000 homes (around three quarters of Christchurch housing stock) sustained damage from the earthquakes. Some areas of Christchurch have been declared not suitable for rebuilding, affecting more than 7,500 residential properties.

Research papers, University of Canterbury Library

A significant portion of economic loss from the Canterbury Earthquake sequence in 2010-2011 was attributed to losses to residential buildings. These accounted for approximately $12B of a total $40B economic losses (Horspool, 2016). While a significant amount of research effort has since been aimed at research in the commercial sector, little has been done to reduce the vulnerability of the residential building stock.