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Research papers, University of Canterbury Library

Environmental stress and disturbance can affect the structure and functioning of marine ecosystems by altering their physical, chemical and biological features. In estuaries, benthic invertebrate communities play important roles in structuring sediments, influencing primary production and biogeochemical flux, and occupying key food web positions. Stress and disturbance can reduce species diversity, richness and abundance, with ecological theory predicting that biodiversity will be at its lowest soon after a disturbance with assemblages dominated by opportunistic species. The Avon-Heathcote Estuary in Christchurch New Zealand has provided a novel opportunity to examine the effects of stress, in the form of eutrophication, and disturbance, in the form of cataclysmic earthquake events, on the structure and functioning of an estuarine ecosystem. For more than 50 years, large quantities (up to 500,000m3/day) of treated wastewater were released into this estuary but in March 2010 this was diverted to an ocean outfall, thereby reducing the nutrient loading by around 90% to the estuary. This study was therefore initially focussed on the reversal of eutrophication and consequent effects on food web structure in the estuary as it responded to lower nutrients. In 2011, however, Christchurch was struck with a series of large earthquakes that greatly changed the estuary. Massive amounts of liquefied sediments, covering up to 65% of the estuary floor, were forced up from deep below the estuary, the estuary was tilted by up to a 50cm rise on one side and a corresponding drop on the other, and large quantities of raw sewage from broken wastewater infrastructure entered the estuary for up to nine months. This study was therefore a test of the potentially synergistic effects of nutrient reduction and earthquake disturbance on invertebrate communities, associated habitats and food web dynamics. Because there was considerable site-to-site heterogeneity in the estuary, the sites in this study were selected to represent a eutrophication gradient from relatively “clean” (where the influence of tidal flows was high) to highly impacted (near the historical discharge site). The study was structured around these sites, with components before the wastewater diversion, after the diversion but before the earthquakes, and after the earthquakes. The eutrophication gradient was reflected in the composition and isotopic chemistry of primary producer and invertebrate communities and the characteristics of sediments across the sample sites. Sites closest to the former wastewater discharge pipe were the most eutrophic and had cohesive organic -rich, fine sediments and relatively depauperate communities dominated by the opportunistic taxa Capitellidae. The less-impacted sites had coarser, sandier sediments with fewer pollutants and far less organic matter than at the eutrophic sites, relatively high diversity and lower abundances of micro- and macro-algae. Sewage-derived nitrogen had became incorporated into the estuarine food web at the eutrophic sites, starting at the base of the food chain with benthic microalgae (BMA), which were found to use mostly sediment-derived nitrogen. Stable isotopic analysis showed that δ13C and δ15N values of most food sources and consumers varied spatially, temporally and in relation to the diversion of wastewater, whereas the earthquakes did not appear to affect the overall estuarine food web structure. This was seen particularly at the most eutrophic site, where isotopic signatures became more similar to the cleaner sites over two-and-a-half years after the diversion. New sediments (liquefaction) produced by the earthquakes were found to be coarser, have lower concentrations of heavy metals and less organic matter than old (existing) sediments. They also had fewer macroinvertebrate inhabitants initially after the earthquakes but most areas recovered to pre-earthquake abundance and diversity within two years. Field experiments showed that there were higher amounts of primary production and lower amounts of nutrient efflux from new sediments at the eutrophic sites after the earthquakes. Primary production was highest in new sediments due to the increased photosynthetic efficiency of BMA resulting from the increased permeability of new sediments allowing increased light penetration, enhanced vertical migration of BMA and the enhanced transport of oxygen and nutrients. The reduced efflux of NH4-N in new sediments indicated that the capping of a large portion of eutrophic old sediments with new sediments had reduced the release of legacy nutrients (originating from the historical discharge) from the sediments to the overlying water. Laboratory experiments using an array of species and old and new sediments showed that invertebrates altered levels of primary production and nutrient flux but effects varied among species. The mud snail Amphibola crenata and mud crab Austrohelice crassa were found to reduce primary production and BMA biomass through the consumption of BMA (both species) and its burial from bioturbation and the construction of burrows (Austrohelice). In contrast, the cockle Austrovenus stutchburyi did not significantly affect primary production and BMA biomass. These results show that changes in the structure of invertebrate communities resulting from disturbances can also have consequences for the functioning of the system. The major conclusions of this study were that the wastewater diversion had a major effect on food web dynamics and that the large quantities of clean and unpolluted new sediments introduced to the estuary during the earthquakes altered the recovery trajectory of the estuary, accelerating it at least throughout the duration of this study. This was largely through the ‘capping’ effect of the new liquefied, coarser-grained sediments as they dissipated across the estuary and covered much of the old organic-rich eutrophic sediments. For all aspects of this study, the largest changes occurred at the most eutrophic sites; however, the surrounding habitats were important as they provided the context for recovery of the estuary, particularly because of the very strong influence of sediments, their biogeochemistry, microalgal and macroalgal dynamics. There have been few studies documenting system level responses to eutrophication amelioration and to the best on my knowledge there are no other published studies examining the impacts of large earthquakes on benthic communities in an estuarine ecosystem. This research gives valuable insight and advancements in the scientific understanding of the effects that eutrophication recovery and large-scale disturbances can have on the ecology of a soft-sediment ecosystem.

Videos, UC QuakeStudies

A video clip of two large-scale, temporary structures, titled Synthesis and Aurora, being installed by students from CPIT and Unitec. The installations were part of CityUps - a 'city of the future for one night only', and the main event of FESTA 2014.

Audio, Radio New Zealand

It's been revealed that not a single one of New Zealand's 315 police buildings constructed before 2011 have had a full earthquake safety check. Canterbury's district health buildings and a central Wellington cinema are among other major structures needing checks. Phil Pennington joins us with the details.

Research papers, University of Canterbury Library

Drywalls are the typical infill or partitions used in new structures. They are usually located within structural frames and/or between upper and lower floor slabs in buildings. Due to the materials used in their construction, unlike masonry blocks, they can be considered as light non-structural infill/partition walls. These types of walls are especially popular in New Zealand and the USA. In spite of their popularity, little is known about their in-plane cyclic behaviour when infilled within a structural frame. The cause of this lack of knowledge can be attributed to the typical assumption that they are weak non-structural elements and are not expected to interact with the surrounding structural system significantly. However, recent earthquakes have repeatedly shown that drywalls interact with the structure and suffer severe damage at very low drift levels. In this paper, experimental test results of two typical drywall types (steel and timber framed) are reported in order to gather further information on; i) their reverse cyclic behaviour, ii) inter-storey drift levels at which they suffer different levels of damage, iii) the level of interaction with the surrounding structural frame system. The drywall specimens were tested using quasi-static reverse cyclic testing protocols within a full scale precast RC frame at the Structures Laboratory of the University of Canterbury.

Research papers, University of Canterbury Library

A series of undrained cyclic direct simple shear (DSS) tests on specimens of sandy silty soils are used to evaluate the effects of fines content, fabric and layered structure on the liquefaction response of sandy soils containing non-plastic fines. Test soils originate from shallow deposits in Christchurch, New Zealand, where severe and damaging manifestations of liquefaction occurred during the 2010-2011 Canterbury earthquakes. A procedure for reconstituting specimens by water sedimentation is employed. This specimen preparation technique involves first pluviation of soil through a water column, and then application of gentle vibrations to the mould (tapping) to prepare specimens with different initial densities. This procedure is applied to prepare uniform specimens, and layered specimens with a silt layer atop a sand layer. Cyclic DSS tests are performed on water-sedimented specimens of two sands, a silt, and sand-silt mixtures with different fines contents. Through this testing program, effects of density, time of vibration during preparation, fines content, and layered structure on cyclic behaviour and liquefaction resistance are investigated. Additional information necessary to characterise soil behaviour is provided by particle size distribution analyses, index void ratio testing, and Scanning Electronic Microscope imaging. The results of cyclic DSS tests show that, for all tested soils, specimens vibrated for longer period of time have lower void ratios, higher relative density, and greater liquefaction resistance. One of the tested sands undergoes significant increase in relative density and liquefaction resistance following prolonged vibration. The other sand exhibits lower increase in relative density and in liquefaction resistance when vibrated for the same period of time. Liquefaction resistance of sand-silt mixtures prepared using this latter sand shows a correlation with relative density irrespective of fines content. In general, however, magnitudes of changes in liquefaction resistance for given variations in vibration time, relative density, or void ratio vary depending on soils under consideration. Characterization based on maximum and minimum void ratios indicates that tested soils develop different structures as fines are added to their respective host sands. These structures influence initial specimen density, strains during consolidation, cyclic liquefaction resistance, and undrained cyclic response of each soil. The different structures are the outcome of differences in particle size distributions, average particle sizes, and particle shapes of the two host sands and of the different relationships between these properties and those of the silt. Fines content alone does not provide an effective characterization of the effects of these factors. Monotonic DSS tests are also performed on specimens prepared by water sedimentation, and on specimens prepared by moist tamping, to identify the critical state lines of tested soils. These critical state lines provide the basis for an alternative interpretation of cyclic DSS tests results within the critical state framework. It is shown that test results imply general consistency between observed cyclic and monotonic DSS soil response. The effects of specimen layering are scrutinised by comparing DSS test results for uniform and layered specimens of the same soils. In this case, only a limited number of tests is performed, and the range of densities considered for the layered specimens is also limited. Caution is therefore required in interpretation of their results. The liquefaction resistance of layered specimens appears to be influenced by the bottom sand layer, irrespective of the global fines content of the specimen. The presence of a layered structure does not result in significant differences in terms of liquefaction response with respect to uniform sand specimens. Cyclic triaxial data for Christchurch sandy silty soils available from previous studies are used to comparatively examine the behaviour observed in the tests of this study. The cyclic DSS liquefaction resistance of water-sedimented specimens is consistent with cyclic triaxial tests on undisturbed specimens performed by other investigators. The two data sets result in similar liquefaction triggering relationships for these soils. However, stress-strain response characteristics for the two types of specimens are different, and undisturbed triaxial specimen exhibit a slower rate of increase in shear strains compared to water-sedimented DSS specimens. This could be due to the greater influence of fabric of the undisturbed specimens.

Videos, UC QuakeStudies

A video about the Christchurch central city in the days after the 4 September 2010 earthquake. The video includes footage of empty streets, and New Zealand Police and Army members guarding the cordons. It also includes footage of engineers checking the safety of buildings.

Other, National Library of New Zealand

Discusses the history, purpose and the structure of the organisation. Also provides links to regional branches, news, newsletters, rural jobs- a resource for prospective employers and employees and resources such as guides, reports and contract and agreement forms. Earthquake related information can be found in the archived instances from September 2010-

Audio, Radio New Zealand

Admiral Thad Allen was the principal federal official in charge after Hurricane Katrina battered the US Gulf Coast in 2005, killing more than 1,700 people and displacing many more. Prime Minister John Key says the structure of the Canterbury Earthquake Recovery Authority was decided upon after an examination of the way other governments responded to disasters like Hurricane Katrina.

Audio, Radio New Zealand

Admiral Thad Allen was the principal federal official in charge after Hurricane Katrina battered the US Gulf Coast in 2005, killing more than 1,700 people and displacing many more. Prime Minister John Key says the structure of the Canterbury Earthquake Recovery Authority was decided upon after an examination of the way other governments responded to disasters like Hurricane Katrina.

Research papers, University of Canterbury Library

Recent severe earthquakes, such as the 2010-2011 Christchurch earthquake series, have put emphasis on building resilience all over the world. To achieve such resilience, procedures for low damage seismic design have been developed to satisfy both life safety requirements and the need to minimize undesirable economic effects of required building repair or structural member replacement following a major earthquake. Seismic resisting systems following this concept are expected to withstand severe earthquakes without requiring major post-earthquake repairs, using isolating mechanisms or sacrificial systems that either do not need repair or are readily repairable or replaceable. These include the sliding hinge joint with asymmetric friction connections (SHJAFCs) in beam-to-column connections of the moment resisting steel frames (MRSFs) and symmetric friction connections (SFCs) in braces of the braced frames. A 9 m tall, configurable three-storey steel framed composite floor building incorporating frictionbased connections is to be tested using two linked bi-directional shake tables at the International joint research Laboratory of Earthquake Engineering (ILEE) facilities, Shanghai, China. The structural systems are configurable, allowing different moment and braced frame structural systems tested in two horizontal directions. The structure is designed and detailed to undergo, at worst, minor damage under a planned series of severe earthquakes.

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

Live monitoring data and simple dynamic reduced-order models of the Christchurch Women’s Hospital (CWH) help explain the performance of the base isolation (BI) system of the hospital during the series of Canterbury earthquakes in 2011-2012. A Park-Wen-Ang hysteresis model is employed to simulate the performance of the BI system and results are compared to measured data recorded above the isolation layer and on the 6th story. Simplified single, two and three degree of freedom models (SDOF, 2DOF and 3DOF) show that the CWH structure did not behave as an isolated but as a fixed-base structure. Comparisons of accelerations and deflections between simulated and monitored data show a good match for isolation stiffness values of approximately two times of the value documented in the design specification and test protocol. Furthermore, an analysis of purely measured data revealed very little to no relative motion across the isolators for large events of moment magnitude scale (Mw) 5.8 and 6.0 that occurred within 3 hours of each other on December 23, 2011. One of the major findings is that the BI system during the seismic events on December 23, 2011 did not yield and that the superstructure performed as a fixed-base building, indicating a need to reevaluate the analysis, design and implementation of these structures.

Research papers, University of Canterbury Library

Recent major earthquakes such as Northridge 1994 and Izmit Kocaeli 1999 highlighted the poor performance of existing buildings constructed prior to the early 1970’s. Low lateral seismic design coefficients and the adopted “working stress design” methodology (essentially an elastic design) lacked any inelastic design considerations, thus leading to inadequate detailing. Insufficient development lengths, lapping within potential plastic hinge regions, lack, or total absence of joint transverse reinforcement, and the use of plain round reinforcement and hooked end anchorages were common throughout the structure. The behaviour is generally dominated by brittle local failure mechanisms (e.g. joint or element shear failures) as well as possible soft-storey mechanisms at a global level. Amongst several possible retrofit interventions, a typical solution is to provide the structure with additional structural walls i.e. external buttressing or column in-fills. Extensive developments on precast, post-tensioned, dissipative systems have shown promise for the use of rocking wall systems to retrofit existing poorly detailed frame structures. In this contribution, the feasibility of such a retrofit intervention is investigated. A displacement-based retrofit procedure is developed and proposed, based on targeting pre-defined performance criteria, such as joint shear and/or column curvature deformation limits. A design example, using the proposed retrofit strategy on a prototype frame is presented. A brief overview on experimental work ongoing at the University of Canterbury investigating the dynamic response of advanced rocking walls for retrofit purposes will be provided.

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

In major seismic events, a number of plan-asymmetric buildings which experienced element failure or structural collapse had twisted significantly about their vertical axis during the earthquake shaking. This twist, known as “building torsion”, results in greater demands on one side of a structure than on the other side. The Canterbury Earthquakes Royal Commission’s reports describe the response of a number of buildings in the February 2011 Christchurch earthquakes. As a result of the catastrophic collapse of one multi-storey building with significant torsional irregularity, and significant torsional effects also in other buildings, the Royal Commission recommended that further studies be undertaken to develop improved simple and effective guides to consider torsional effects in buildings which respond inelastically during earthquake shaking. Separately from this, as building owners, the government, and other stakeholders, are planning for possible earthquake scenarios, they need good estimates of the likely performance of both new and existing buildings. These estimates, often made using performance based earthquake engineering considerations and loss estimation techniques, inform decision making. Since all buildings may experience torsion to some extent, and torsional effects can influence demands on building structural and non-structural elements, it is crucial that demand estimates consider torsion. Building seismic response considering torsion can be evaluated with nonlinear time history analysis. However, such analysis involves significant computational effort, expertise and cost. Therefore, from an engineers’ point of view, simpler analysis methods, with reasonable accuracy, are beneficial. The consideration of torsion in simple analysis methods has been investigated by many researchers. However, many studies are theoretical without direct relevance to structural design/assessment. Some existing methods also have limited applicability, or they are difficult to use in routine design office practice. In addition, there has been no consensus about which method is best. As a result, there is a notable lack of recommendations in current building design codes for torsion of buildings that respond inelastically. There is a need for building torsion to be considered in yielding structures, and for simple guidance to be developed and adopted into building design standards. This study aims to undertaken to address this need for plan-asymmetric structures which are regular over their height. Time history analyses are first conducted to quantify the effects of building plan irregularity, that lead to torsional response, on the seismic response of building structures. Effects of some key structural and ground motion characteristics (e.g. hysteretic model, ground motion duration, etc.) are considered. Mass eccentricity is found to result in rather smaller torsional response compared to stiffness/strength eccentricity. Mass rotational inertia generally decreases the torsional response; however, the trend is not clearly defined for torsionally restrained systems (i.e. large λty). Systems with EPP and bilinear models have close displacements and systems with Takeda, SINA, and flag-shaped models yield almost the same displacements. Damping has no specific effect on the torsional response for the single-storey systems with the unidirectional eccentricity and excitation. Displacements of the single-storey systems subject to long duration ground motion records are smaller than those for short duration records. A method to consider torsional response of ductile building structures under earthquake shaking is then developed based on structural dynamics for a wide range of structural systems and configurations, including those with low and high torsional restraint. The method is then simplified for use in engineering practice. A novel method is also proposed to simply account for the effects of strength eccentricity on response of highly inelastic systems. A comparison of the accuracy of some existing methods (including code-base equivalent static method and model response spectrum analysis method), and the proposed method, is conducted for single-storey structures. It is shown that the proposed method generally provides better accuracy over a wide range of parameters. In general, the equivalent static method is not adequate in capturing the torsional effects and the elastic modal response spectrum analysis method is generally adequate for some common parameters. Record-to-record variation in maximum displacement demand on the structures with different degrees of torsional response is considered in a simple way. Bidirectional torsional response is then considered. Bidirectional eccentricity and excitation has varying effects on the torsional response; however, it generally increases the weak and strong edges displacements. The proposed method is then generalized to consider the bidirectional torsion due to bidirectional stiffness/strength eccentricity and bidirectional seismic excitation. The method is shown to predict displacements conservatively; however, the conservatism decreases slightly for cases with bidirectional excitation compared to those subject to unidirectional excitation. In is shown that the roof displacement of multi-storey structures with torsional response can be predicted by considering the first mode of vibration. The method is then further generalized to estimate torsional effects on multi-storey structure displacement demands. The proposed procedure is tested multi-storey structures and shown to predict the displacements with a good accuracy and conservatively. For buildings which twist in plan during earthquake shaking, the effect of P-Δλ action is evaluated and recommendations for design are made. P-Δλ has more significant effects on systems with small post- yield stiffness. Therefore, system stability coefficient is shown not to be the best indicator of the importance of P-Δλ and it is recommended to use post-yield stiffness of system computed with allowance for P-Δλ effects. For systems with torsional response, the global system stability coefficient and post- yield stiffness ration do not reflect the significance of P-Δλ effects properly. Therefore, for torsional systems individual seismic force resisting systems should be considered. Accuracy of MRSA is investigated and it is found that the MRSA is not always conservative for estimating the centre of mass and strong edge displacements as well as displacements of ductile systems with strength eccentricity larger than stiffness eccentricity. Some modifications are proposed to get the MRSA yields a conservative estimation of displacement demands for all cases.

Audio, Radio New Zealand

The Australian Rugby Union is supporting a call by its New Zealand counterpart for changes to the World Cup cost structure, Canterbury's estimated 30 billion-dollar earthquake rebuild could receive a kick-start from the giant China Development Bank, When it comes to the battlefield of illness and infections, women are far more robust than their male counterparts.

Research papers, University of Canterbury Library

Several concrete cladding panels were damaged during the 2011 Christchurch Earthquakes in New Zealand. Damage included partial collapse of panels, rupture of joint sealants, cracking and corner crushing. Installation errors, faulty connections and inadequate detailing were also contributing factors to the damage. In New Zealand, two main issues are considered in order to accommodate story drifts in the design of precast cladding panels: 1) drift compatibility of tieback or push-pull connections and 2) drift compatibility of corner joints. Tieback connections restrain the panels in the out-of-plane direction while allowing in-plane translation with respect to the building frame. Tieback connections are either in the form of slots or oversized holes or ductile rods usually located at the top of the panels. Bearing connections are also provided at the bottom of panels to transfer gravity loads. At the corners of a building, a vertical joint gap, usually filled with sealants, is provided between the two panels on the two orthogonal sides to accommodate the relative movement. In cases where the joint gap is not sufficient to accommodate the relative movements, panels can collide, generating large forces and the likely failure of the connections. On the other hand, large gaps are aesthetically unpleasing. The current design standards appear to recognize these issues but then leave most of the design and detailing to the discretion of the designers. In the installation phase, the alignment of panels is one of the main challenges faced by installers (and/or contractors). Many prefer temporary props to guide, adjust and hold the panels in place whilst the bearing connections are welded. Moreover, heat generated from extensive welding can twist the steel components inducing undesirable local stresses in the panels. Therefore, the installation phase itself is time-consuming, costly and prone to errors. This paper investigates the performance of a novel panel system that is designed to accommodate lateral inter-story drift through a ‘rocking’ motion. In order to gauge the feasibility of the system, six 2m high precast concrete panels within a single-story steel frame structure have been tested under increasing levels of lateral cyclic drift at the University of Canterbury, New Zealand. Three different panel configurations are tested: 1) a panel with return cover and a flat panel at a corner under unidirectional loading, 2) Two adjacent flat panels under unidirectional loading, and 3) Two flat panels at another oblique corner under bidirectional loading. A vertical seismic joint of 25 mm, filled with one-stage joint sealant, is provided between two of the panels. The test results show the ability of the panels with ‘rocking’ connection details to accommodate larger lateral drifts whilst allowing for smaller vertical joints between panels at corners, quick alignment and easy placement of panels without involving extensive welding on site.

Audio, Radio New Zealand

The Earthquake Commission (EQC) criticised for misleading and inadequate measurements on housing foundations when assessing damage to Canterbury homes; Wellington historic building champions vow to save heritage structure in the capital; the spread of didymo in Fiordland; Defence Force sentencing today after drowning last year; the censorship of Maniac, arty audiences only please, and; the PM changes tack on working with NZ First.

Research papers, University of Canterbury Library

In recent Canterbury earthquakes, structures have performed well in terms of life safety but the estimated total cost of the rebuild was as high as $40 billion. The major contributors to this cost are repair/demolition/rebuild cost, the resulting downtime and business interruption. For this reason, the authors are exploring alternate building systems that can minimize the downtime and business interruption due to building damage in an earthquake; thereby greatly reducing the financial implications of seismic events. In this paper, a sustainable and demountable precast reinforced concrete (RC) frame system in which the precast members are connected via steel tubes/plates or steel angles/plates and high strength friction grip (HSFG) bolts is introduced. In the proposed system, damaged structural elements in seismic frames can be easily replaced with new ones; thereby making it an easily and quickly repairable and a low-loss system. The column to foundation connection in the proposed system can be designed either as fixed or pinned depending on the requirement of strength and stiffness. In a fixed base frame system, ground storey columns will also be damaged along with beams in seismic events, which are to be replaced after seismic events; whereas in a pin base frame only beams (which are easy to replace) will be damaged. Low to medium rise (3-6 storey) precast RC frame buildings with fixed and pin bases are analyzed in this paper; and their lateral capacity, lateral stiffness and natural period are scrutinized to better understand the pros and cons of the demountable precast frame system with fixed and pin base connections.

Images, UC QuakeStudies

Broken windows on the Orion building on Manchester Street. The photographer comments, "Bob Brown's Hi-Fi was damaged, as you can see, in the Christchurch earthquake on the 22 February 2011. At lot of buildings in the area have been demolished, but this art deco style structure might have not have been put on the demolition list yet".

Videos, UC QuakeStudies

A video of a media tour inside the earthquake-damaged Hotel Grand Chancellor. The video includes footage of the eastern side of the ground floor of the hotel, the stairwells, some of the rooms, and the view through an opening in the side of the building. It also includes an interview with Jack Harris from Fletchers Construction about the work that is being done to support the structure.

Research papers, University of Canterbury Library

The objective of this project is to collect perishable seismic response data from the baseisolated Christchurch Women's Hospital. The strong and continuing sequence of aftershocks presents a unique opportunity to capture high-fidelity data from a modern base-isolated facility. These measurements will provide quantitative information required to assess the mechanisms at play in this and in many other seismically-isolated structures.