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Research papers, University of Canterbury Library

This study analyses the Earthquake Commission’s (EQC) insurance claims database to investigate the influence of seismic intensity and property damage resulting from the Canterbury Earthquake Sequence (CES) on the repair costs and claim settlement duration for residential buildings. Firstly, the ratio of building repair cost to its replacement cost was expressed as a Building Loss Ratio (BLR), which was further extended to Regional Loss Ratio (RLR) for greater Christchurch by multiplying the average of all building loss ratios with the proportion of building stock that lodged an insurance claim. Secondly, the total time required to settle the claim and the time taken to complete each phase of the claim settlement process were obtained. Based on the database, the regional loss ratio for greater Christchurch for three events producing shakings of intensities 6, 7, and 8 on the modified Mercalli intensity scale were 0.013, 0.066, and 0.171, respectively. Furthermore, small (less than NZD15,000), medium (between NZD15,000 and NZD100,000), and large (more than NZD100,000) claims took 0.35-0.55, 1.95-2.45, and 3.35-3.85 years to settle regardless of the building’s construction period and earthquake intensities. The number of claims was also disaggregated by various building characteristics to evaluate their relative contribution to the damage and repair costs.

Research papers, University of Canterbury Library

Slender precast concrete wall panels are currently in vogue for the construction of tall single storey warehouse type buildings. Often their height to thickness ratio exceed the present New Zealand design code (NZS 3101) limitations of 30:1. Their real performance under earthquake attack is unknown. Therefore, this study seeks to assess the dynamic performance of slender precast concrete wall panels with different base connection details. Three base connections (two fixed base and one rocking) from two wall specimens with height to thickness ratios of 60:1 were tested under dynamic loading. The two fixed based walls had longitudinal steel volumes of 1.27% to 0.54% and were tested on the University of Canterbury shaking table to investigate their proneness to out-of-plane buckling. Based on an EUler-type theoretical formula derived as part of the study, an explanation is made as to why walls with high in-plane capacity are more prone to buckling. The theory was validated against the present and past experimental evidence. The rocking base connection designed and built in accordance with a damage avoidance philosophy was tested on the shaking table in a similar fashion to the fixed base specimens. Results show that in contrast with their fixed base counterparts, rocking walls can indeed fulfil a damage-free design objective while also remaining stable under strong earthquake ground shaking.

Research papers, University of Canterbury Library

Recently developed performance-based earthquake engineering framework, such as one provided by PEER (Deierlein et al. 2003), assist in the quantification in terms of performance such as casualty, monetary losses and downtime. This opens up the opportunity to identify cost-effective retrofit/rehabilitation strategies by comparing upfront costs associated with retrofit with the repair costs that can be expected over time. This loss assessment can be strengthened by learning from recent earthquakes, such as the 2010 Canterbury and 2016 Kaikoura earthquakes. In order to investigate which types of retrofit/rehabilitation strategies may be most cost-effective, a case study building was chosen for this research. The Pacific Tower, a 22-storey EBF apartment located within the Christchurch central business district (CBD), was damaged and repaired during the 2010 Canterbury earthquake series. As such, by taking hazard levels accordingly (i.e. to correspond to the Christchurch CBD), modelling and analysing the structure, and considering the vulnerability and repair costs of its different components, it is possible to predict the expected losses of the aforementioned building. Using this information, cost-effective retrofit/rehabilitation strategy can be determined. This research found that more often than not, it would be beneficial to improve the performance of valuable non-structural components, such as partitions. Although it is true that improving such elements will increase the initial costs, over time, the benefits gained from reduced losses should be expected to overcome the initial costs. Aftershocks do increase the predicted losses of a building even in lower intensities due to the fact that non-structural components can get damaged at such low intensities. By comparing losses computed with and without consideration of aftershocks for a range of historical earthquakes, it was found that the ratio between losses due to main shock with aftershocks to the losses due to the main shock only tended to increase with increasing main shock magnitude. This may be due to the fact that larger magnitude earthquakes tend to generate larger magnitude aftershocks and as those aftershocks happen within a region around the main shock, they are more likely to cause intense shaking and additional damage. In addition to this observation, it was observed that the most significant component of loss of the case study building was the non-structural partition walls.

Research papers, University of Canterbury Library

Natural disasters are increasingly disruptive events that affect livelihoods, organisations, and economies worldwide. Research has identified the impacts and responses of organisations to different types of natural disasters, and have outlined factors, such as industry sector, that are important to organisational vulnerability and resilience. One of the most costly types of natural disasters in recent years has been earthquakes, and yet to date, the majority of studies have focussed on the effects of earthquakes in urban areas, while rural organisational impact studies have primarily focused on the effects of meteorological and climatic driven hazards. As a result, the likely impacts of an earthquake on rural organisations in a developed context is unconstrained in the literature. In countries like New Zealand, which have major earthquakes and agricultural sectors that are significant contributors to the economy, it is important to know what impacts an earthquake event would have on the rural industries, and how these impacts compare to that of a more commonly analysed, high-frequency event. In September of 2010, rural organisations in Canterbury experienced the 4 September 2010 Mw 7.1 `Darfield' earthquake and the associated aftershocks, which came to be known as the Canterbury earth- quake sequence. The earthquake sequence caused intense ground shaking, creating widespread critical service outages, structural and non-structural damage to built infrastructure, as well as ground surface damage from ooding, liquefaction and surface rupture. Concurrently on September 18 2010, rural organisations in Southland experienced an unseasonably late snowstorm and cold weather snap that brought prolonged sub-zero temperatures, high winds and freezing rain, damaging structures in the City of Invercargill and causing widespread livestock losses and production decreases across the region. This thesis documents the effects of the Canterbury earthquake sequence and Southland snowstorm on farming and rural non-farming organisations, utilizing comparable methodologies to analyse rural organisational impacts, responses and recovery strategies to natural disasters. From the results, a short- term impact assessment methodology is developed for multiple disasters. Additionally, a regional asset repair cost estimation model is proposed for farming organisations following a major earthquake event, and the use of social capital in rural organisational recovery strategies following natural disasters is analysed.

Images, UC QuakeStudies

Two images of a house, taken before and after the earthquakes. In the after photograph the chimneys are gone, a column supporting the car port has partly collapsed, windows are broken, and the previously neat lawn and driveway are overgrown. The photographer comments, "This was a house that I was selling up to the September 2010 earthquake in Christchurch. It was on Avonside Drive, which was an area that has been badly hit in every earthquake that has hit the area. In the September quake parts of the house moved in different directions and one of the upstairs doors had to be smashed open to release one of the sons from his bedroom. This occurred in the dark with numerous aftershocks shaking the house. Liquefaction poured up through the floor and flowed down the drive. Everyone got out OK, but soon after the house was red stickered meaning it was dangerous to enter. The house was looted many times even though there was constant police patrols. When the most violent earthquake occurred on 22 February 2012 both the tall heavy chimneys came crashing through into the living areas. Subsequent earthquakes and aftershocks have caused one of the brick fence pillars to fall and the front garage pillar to break up and twist. The family's troubles did not end there. They moved into the home of one of their parents and this mansion of a home was so badly affected by the February earthquake that no one could enter to collect any of their or their parents' belongings. They now own a new home, which they are fond of except when the ground shakes yet again. There has been to date 10,712 earthquakes and aftershocks since 4 September 2010".

Images, Alexander Turnbull Library

Text reads 'Earthquake survivors' and amongst the rubble of a collapsed building is a man representing 'courage' who is trapped by a concrete slab and a woman with severed legs who is reaching out to help him and who represents 'compassion'. Context - The very severe Christchurch earthquake of 22 February 2011 in which probably more than 200 people died and an enormous amount of structural damage has been done. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

Cartoon drawn in the style of a pen and ink drawing of the broken Christchurch Cathedral. One version has 'RIP' printed above the non-existant spire and the second has 'RIP' and the words 'Rest in Pieces'. A decision has been made to demolish the cathedral which was severely damaged by the earthquakes of 2010 and 2011. Two versions of this cartoon are available Title from file name Quantity: 2 digital cartoon(s).

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).

Audio, Radio New Zealand

TVs, shopping trolleys, beds, mattresses, even a gun. That is just some of the rubbish found by residents surrounding Christchurch's residential red zone. The area used to be filled with houses, but damage after the Canterbury earthquakes forced thousands of homes to be demolished. While many of the old suburban roads remain, the area now resembles a park. But it is now attracting those wanting to dump their rubbish for free - and Land Information NZ, which controls the land, has removed 25 tonnes of trash since January. Residents have had enough as well - with some taking matters into their own hands. Checkpoint reporter Logan Church has the story.

Audio, Radio New Zealand

Christchurch red zone residents say the area is experiencing an increasing amount of petty crime and dumped rubbish, due to a lack of people. The red zone was established after thousands of houses - and the land underneath them - suffered severe damage in the 2010 and 2011 earthquakes. Last year (2019), a Regeneration Plan for the area was signed off by the government - which included building walkways, cycleways, forests, wetlands, and sport and recreation areas. That's all designed to get people back into the red zone area - but much of the work is still years away. Logan Church met a resident who told him that in the meantime, things are deteriorating.

Audio, Radio New Zealand

Ngai Tahu says its people are turning to the tribe for help with legal and engineering advice about their earthquake-damaged homes in Christchurch; The Chairperson of the Maori Midwives Collective Nga Maia, says the earthquake a year ago forced the organisation to start its administrative operations from scratch; Efforts are underway to find out how many Maori left Christchurch after the earthquake; The Ngai Tahu hapu, Ngai Tuahuriri in Christchurch, will be welcoming the Governor-General to Rehua Marae this morning to commemorate the anniversary of last year's earthquake; Christchurch will hear today whether it'll be hosting the biggest Maori performance event on the calendar - Te Matatini National Festival.

Audio, Radio New Zealand

There's good news of sorts on the building-inspection front in Auckland. After nearly seven days of fanning out across the city inspecting damaged buildings - the biggest such deployment of building inspectors since the Christchurch earthquake emergency - the operation will be scaled back this weekend.  There are currently around 95 inspectors in the field who have checked 3,500 buildings. As of 6pm last night 190 buildings were red stickered, and a further 790 yellow stickered. The most red stickered areas are Mount Albert/Mt Eden with 54 and the North Shore with 32. Auckland Council general manager building consents Ian McCormick spoke to Corin Dann. 

Images, UC QuakeStudies

A view down Beresford Street in New Brighton, looking west towards the city at sunset. The photographer comments, "On the other side of the Avon river from New Brighton is the Bexley red zone. Here numerous earthquake damaged streets of houses will be flattened due to it being to uneconomical in the current climate to repair the land to be suitable for housing. There is a campaign at the moment to try and convert all this red zone land, which is mainly adjacent to the Avon river to a giant park".

Images, UC QuakeStudies

Large cracks run through the brick cladding of this house in Wainoni. The photographer comments, "During the numerous earthquakes in Christchurch the land which ran alongside the Avon river on Avonside Drive slumped towards the waterway. Houses which were wooden framed and had an external brick veneer started to sink into the liquefied soil. This caused the brick walls to crack, but the houses' occupants though shook up were saved by the wooden framework from the houses collapsing on them".

Images, UC QuakeStudies

A photograph of the former site of Westende Jewellers and Alva Rados, on the corner of Manchester Street and Worcester Street. The building was badly-damaged in the 4 September earthquake and was demolished soon afterwards. A two-storey building was built on the site and completed in July 2012. The building then had to be removed when the decision was made to widen Manchester Street as part of the draft transport plan for central Christchurch. The photograph was modelled after an image taken by Ian McGregor from Fairfax Media in September 2010.

Images, UC QuakeStudies

A photograph of the former site of Westende Jewellers and Alva Rados, on the corner of Manchester Street and Worcester Street. The building was badly-damaged in the 4 September earthquake and was demolished soon afterwards. A two-storey building was built on the site and completed in July 2012. The building then had to be removed when the decision was made to widen Manchester Street as part of the draft transport plan for central Christchurch. The photograph was modelled after an image taken by Ian McGregor from Fairfax Media in September 2010.

Images, UC QuakeStudies

Photograph captioned by Fairfax, "Teddy time: A Whanganui man has sent dozens of teddy bears to Rangiora to be distributed to children affected by the Canterbury earthquake. Ted Cheriton sent the teddies to National MP Kate Wilkinson's office to be distributed. Ms Wilkinson said it was a fantastic gesture. 'I am sure they will be welcome in Kaiapoi and beach settlements where damage from the earthquake has severely affected many families', she said. 'Hopefully these teddies will bring a smile to some young children and cheer them up in what has been a very trying and traumatic time'".

Audio, Radio New Zealand

Ravenscar House Museum holds an extraordinary, previously private art collection. The new building has been gifted to Christchurch by art collectors Susan Wakefield and her late husband Jim. The art remains in the ownership of the Ravenscar Trust.  Artists in the collection include Colin McCahon, Bill Sutton and Frances Hodgkins. The treasures were previously in the Wakefield's Christchurch home which suffered irreparable earthquake damage. They're now displayed in the purpose-designed and built Ravenscar House Museum in the city's Arts precinct. The story of the art and artefacts is told in in the book - Ravenscar House: A Biography, written by Christchurch journalist and writer Sally Blundell.  

Research papers, University of Canterbury Library

The Canterbury earthquakes caused huge amounts of damage to Christchurch and the surrounding area and presented a very challenging situation for both insurers and claimants. While tourism has suffered significant losses as a result, particularly due to the subsequent decrease in visitor numbers, the Canterbury region was very fortunate to have high levels of insurance coverage. This report, based on data gathered from tourism operators on the ground in Canterbury, looks at how this sector has been affected by the quakes, claims patterns, and the behaviour and perceptions of tourism operators about insurance.

Audio, Radio New Zealand

Gulls are well known for swooping in and flogging food off your plate or picnic and now they are making a complete menace of themselves in Christchurch's New Regent street. Local businesses are being over-run by the red and black-billed gulls that are nesting on the rooves of buildings along the street, swooping and pooping all over the place. It's not the first time they've invaded, they started breeding in 2019 in an earthquake damaged building on the corner of Armagh and New Regent streets. The problem is both the red and black-billed gulls are protected. Casey Alderson from Belle Cafe spoke to Lisa Owen.

Research papers, The University of Auckland Library

The current seismic design practice for reinforced concrete (RC) walls has been drawn into question following the unsatisfactory performance of several RC wall buildings during the Canterbury earthquakes. An overview of current research being undertaken at the University of Auckland into the seismic behaviour of RC walls is presented. The main objectives of this research project are to understand the observed performance of RC walls in Christchurch, quantify the seismic loads on RC walls, and developed improved design procedures for RC walls that will assist in revisions to the New Zealand Concrete Structures Standard. A database summarising the performance of RC wall buildings in the Christchurch CBD was collated to identify damage modes and case-study buildings. A detailed investigation is underway to verify the seismic performance of lightly reinforced concrete walls and initial numerical modeling and small-scale tests are presented in addition to details of planned experimental tests of RC walls. Numerical modelling is being used to understand the potential influence that interactions between walls and other structural elements have on the seismic response of buildings and the loads generated on RC walls. The results from finite element analysis of a severely damaged RC wall in Christchurch highlighted the effect that the floor diaphragms have on the distribution of shear stains in the wall.

Images, Alexander Turnbull Library

Prime Minister John Key drives a tractor to which is attached a crane and a huge demolition ball in the shape of MP Gerry Brownlee's head; the ball smashes against a historic building bringing stone pediments down. Context - Gerry Brownlee, who is Earthquake Recovery Minister, has caused a stir by suggesting that if he had his way some of Christchurch's older buildings would be "down tomorrow". He also said the price of saving some historic buildings badly damaged in the February 22 earthquake was too high. People had died in the quake because of attempts to save historic buildings badly damaged in the September 4 quake. Brownlee said he had no regrets despite the stir his comments caused - but he was annoyed by suggestions the Cathedral and Riccarton House were among buildings he thought should be bowled. He believed those buildings should be saved, and they would be. "I'm not a philistine; I was chairman of the trust that actually saved Riccarton House from the bulldozers in 1990. "I understand conservation architecture very well and I do have an appreciation of heritage buildings." Original cartoon held at A-474-048 Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

The cartoon shows a monstrous machine with an enormous crushing ball attached to a giant crane. It moves past a signpost that points towards Christchurch. A man watches and tells his friend 'Gerry Brownlee borrowed it from Auckland! Context - Brownlee has caused a stir by suggesting that if he had his way some of Christchurch's older buildings would be "down tomorrow". He also said the price of saving some historic buildings badly damaged in the February 22 earthquake was too high. People had died in the quake because of attempts to save historic buildings badly damaged in the September 4 quake. Brownlee said he had no regrets despite the stir his comments caused - but he was annoyed by suggestions the Cathedral and Riccarton House were among buildings he thought should be bowled. He believed those buildings should be saved, and they would be. "I'm not a philistine; I was chairman of the trust that actually saved Riccarton House from the bulldozers in 1990. "I understand conservation architecture very well and I do have an appreciation of heritage buildings." Colour and black and white versions available Quantity: 2 digital cartoon(s).

Research papers, The University of Auckland Library

As part of the ‘Project Masonry’ Recovery Project funded by the New Zealand Natural Hazards Research Platform, commencing in March 2011, an international team of researchers was deployed to document and interpret the observed earthquake damage to masonry buildings and to churches as a result of the 22nd February 2011 Christchurch earthquake. The study focused on investigating commonly encountered failure patterns and collapse mechanisms. A brief summary of activities undertaken is presented, detailing the observations that were made on the performance of and the deficiencies that contributed to the damage to approximately 650 inspected unreinforced clay brick masonry (URM) buildings, to 90 unreinforced stone masonry buildings, to 342 reinforced concrete masonry (RCM) buildings, to 112 churches in the Canterbury region, and to just under 1100 residential dwellings having external masonry veneer cladding. Also, details are provided of retrofit techniques that were implemented within relevant Christchurch URM buildings prior to the 22nd February earthquake. In addition to presenting a summary of Project Masonry, the broader research activity at the University of Auckland pertaining to the seismic assessment and improvement of unreinforced masonry buildings is outlined. The purpose of this outline is to provide an overview and bibliography of published literature and to communicate on-going research activity that has not yet been reported in a complete form. http://sesoc.org.nz/conference/programme.pdf

Research papers, University of Canterbury Library

Surface rupture of the previously unrecognised Greendale Fault extended west-east for ~30 km across alluvial plains west of Christchurch, New Zealand, during the Mw 7.1 Darfield (Canterbury) earthquake of September 2010. Surface rupture displacement was predominantly dextral strike-slip, averaging ~2.5 m, with maxima of ~5 m. Vertical displacement was generally less than 0.75 m. The surface rupture deformation zone ranged in width from ~30 to 300 m, and comprised discrete shears, localised bulges and, primarily, horizontal dextral flexure. About a dozen buildings, mainly single-storey houses and farm sheds, were affected by surface rupture, but none collapsed, largely because most of the buildings were relatively flexible and resilient timber-framed structures and also because deformation was distributed over a relatively wide zone. There were, however, notable differences in the respective performances of the buildings. Houses with only lightly-reinforced concrete slab foundations suffered moderate to severe structural and non-structural damage. Three other buildings performed more favourably: one had a robust concrete slab foundation, another had a shallow-seated pile foundation that isolated ground deformation from the superstructure, and the third had a structural system that enabled the house to tilt and rotate as a rigid body. Roads, power lines, underground pipes, and fences were also deformed by surface fault rupture and suffered damage commensurate with the type of feature, its orientation to the fault, and the amount, sense and width of surface rupture deformation.

Research papers, University of Canterbury Library

The magnitude Mw 6.2 earthquake of February 22nd 2011 that struck beneath the city of Christchurch, New Zealand, caused widespread damage and was particularly destructive to the Central Business District (CBD). The shaking caused major damage, including collapses of structures, and initiated ground failure in the form of soil liquefaction and consequent effects such as sand boils, surface flooding, large differential settlements of buildings and lateral spreading of ground towards rivers were observed. A research project underway at the University of Canterbury to characterise the engineering behaviour of the soils in the region was influenced by this event to focus on the performance of the highly variable ground conditions in the CBD. This paper outlines the methodology of this research to characterise the key soil horizons that underlie the CBD that influenced the performance of important structures during the recent earthquakes, and will influence the performance of the rebuilt city centre under future events. The methodology follows post-earthquake reconnaissance in the central city, a desk study on ground conditions, site selection, mobilisation of a post-earthquake ground investigation incorporating the cone penetration test (CPT), borehole drilling, shear wave velocity profiling and Gel-push sampling followed by a programme of laboratory testing including monotonic and cyclic testing of the soils obtained in the investigation. The research is timely and aims to inform the impending rebuild, with appropriate information on the soils response to dynamic loading, and the influence this has on the performance of structures with various foundation forms.

Research papers, University of Canterbury Library

On February 22, 2011, a magnitude Mw 6.2 earthquake affected the Canterbury region, New Zealand, resulting in many fatalities. Liquefaction occurred across many areas, visible on the surface as ‘‘sand volcanoes’’, blisters and subsidence, causing significant damage to buildings, land and infrastructure. Liquefaction occurred at a number of sites across the Christchurch Boys High School sports grounds; one area in particular contained a piston ground failure and an adjacent silt volcano. Here, as part of a class project, we apply near-surface geophysics to image these two liquefaction features and determine whether they share a subsurface connection. Hand auger results enable correlation of the geophysical responses with the subsurface stratigraphy. The survey results suggest that there is a subsurface link, likely via a paleo-stream channel. The anomalous responses of the horizontal loop electromagnetic survey and electrical resistivity imaging highlight the disruption of the subsurface electrical properties beneath and between the two liquefaction features. The vertical magnetic gradient may also show a subtle anomalous response in this area, however the results are inconclusive. The ground penetrating radar survey shows disruption of the subsurface stratigraphy beneath the liquefaction features, in particular sediment mounding beneath the silt ejection (‘‘silt volcano’’) and stratigraphic disruption beneath the piston failure. The results indicate how near-surface geophysics allow the characteristics of liquefaction in the subsurface to be better understood, which could aid remediation work following liquefaction-induced land damage and guide interpretation of geophysical surveys of paleoliquefaction features.

Research papers, University of Canterbury Library

The greater Wellington region, New Zealand, is highly vulnerable to large earthquakes. While attention has been paid to the consequences of earthquake damage to road, electricity and water supply networks, the consequences of wastewater network damage for public health, environmental health and habitability of homes remain largely unknown for Wellington City. The Canterbury and Kaikōura earthquakes have highlighted the vulnerability of sewerage systems to disruption during a disaster. Management of human waste is one of the critical components of disaster planning to reduce faecal-oral transmission of disease and exposure to disease-bearing vectors. In Canterbury and Kaikōura, emergency sanitation involved a combination of Port-a-loos, chemical toilets and backyard long-drops. While many lessons may be learned from experiences in Canterbury earthquakes, it is important to note that isolation is likely to be a much greater factor for Wellington households, compared to Christchurch, due to the potential for widespread landslides in hill suburbs affecting road access. This in turn implies that human waste may have to be managed onsite, as options such as chemical toilets and Port-a-loos rely completely on road access for delivering chemicals and collecting waste. While some progress has been made on options such as emergency composting toilets, significant knowledge gaps remain on how to safely manage waste onsite. In order to bridge these gaps, laboratory tests will be conducted through the second half of 2019 to assess the pathogen die-off rates in the composting toilet system with variables being the type of carbon bulking material and the addition of a Bokashi composting activator.

Research papers, University of Canterbury Library

Seismic isolation is an effective technology for significantly reducing damage to buildings and building contents. However, its application to light-frame wood buildings has so far been unable to overcome cost and technical barriers such as susceptibility to movement during high-wind loading. The precursor to research in the field of isolation of residential buildings was the 1994 Northridge Earthquake (6.7 MW) in the United States and the 1995 Kobe Earthquake (6.9 MW) in Japan. While only a small number of lives were lost in residential buildings in these events, the economic impact was significant with over half of earthquake recovery costs given to repair and reconstruction of residential building damage. A value case has been explored to highlight the benefits of seismically isolated residential buildings compared to a standard fixed-base dwellings for the Wellington region. Loss data generated by insurance claim information from the 2011 Christchurch Earthquake has been used by researchers to determine vulnerability functions for the current light-frame wood building stock. By further considering the loss attributed to drift and acceleration sensitive components, and a simplified single degree of freedom (SDOF) building model, a method for determining vulnerability functions for seismic isolated buildings was developed. Vulnerability functions were then applied directly in a loss assessment using the GNS developed software, RiskScape. Vulnerability was shown to dramatically reduce for isolated buildings compared to an equivalent fixed-base building and as a result, the monetary savings in a given earthquake scenario were significant. This work is expected to drive further interest for development of solutions for the seismic isolation of residential dwellings, of which one option is further considered and presented herein.

Research papers, University of Canterbury Library

Earthquakes cause significant damage to buildings due to strong vibration of the ground. Levitating houses using magnets and electromagnets would provide a complete isolation of ground motion for protecting buildings from seismic damage. Two types of initial configuration for the electromagnet system were proposed with the same air gap (10mm) between the electromagnet and reluctance plate. Both active and passive controller are modelled to investigate the feasibility of using a vibration control system for stabilizing the magnetic system within the designed air gap (10mm) in the vertical direction. A nonlinear model for the magnetic system is derived to implement numerical simulation of structural response under the earthquake record in Christchurch Botanic Gardens on 21 February 2011. The performance of the uncontrolled and the controlled systems are compared and the optimal combination of control gains are determined for the PID active controller. Simulation results show both active PID controller with constant and nonlinear attracting force are able to provide an effective displacement control within the required air gap (+/-5mm). The maximum control force demand for the PID controller in the presence of nonlinear attracting force is 4.1kN, while the attracting force in equilibrium position is 10kN provided by the electromagnet. These results show the feasibility of levitating a house using the current electromagnet and PID controller. Finally, initial results of passive control using two permanent magnets or dampers show the structural responses can be effectively reduced and centralized to +/-1mm using a nonlinear centring barrier function.