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Videos, UC QuakeStudies

A video about the Christchurch City Council housing complex on Conference Street in the Christchurch central city. The housing complex was unoccupied after the 22 February 2011 earthquake despite the housing shortage. Christchurch City Council said that the vacant units could not be lived in because of structural damage or damage to services. However, the building has been checked by structural engineers and many of the rooms have been deemed safe to occupy.

Videos, UC QuakeStudies

A video of a helicopter using a monsoon bucket to wash loose debris off a cliff in Redcliffs. The debris is from an earthquake-damaged building on the edge of the cliff which has had to be urgently demolished after wet weather and aftershocks made it unstable. The video also includes an interview with Brenden Winder, Red Zone Cordon and Access Manager at CERA, about the removal of the debris and the need to check other properties.

Videos, UC QuakeStudies

A video of a tour of the historic Canterbury Club building on Cambridge Terrace. The club will reopen on 9 June 2012, after an intensive rebuild and restoration process which has fixed the damage from the 22 February 2011 earthquake. The video also includes an interview with Dr Brent Stanley, the Canterbury Club President. Stanley talks about the strengthening work that was done in 2009, as well as the history of the club.

Videos, UC QuakeStudies

A video of an interview with Prime Minister John Key about several topical issues. One of these issues is the housing crisis in Christchurch. Key talks about fast tracking the release of land in Christchurch, making sure there are enough resources in the city for building, and working with the Christchurch City Council around consenting. He also talks about the possibility of the National Party winning the Christchurch East by-election.

Videos, UC QuakeStudies

A video of interviews with members of the public about which option they prefer for the restoration of the ChristChurch Cathedral. The options considered are those unveiled by the Anglican Church: the restoration option which would restore the current cathedral; the traditional option which would reinterpret the original cathedral in modern materials; and the contemporary option which would create a new building featuring a lightweight timber frame, more glazing, and modern interiors.

Videos, UC QuakeStudies

A video of an interview with Tom Thomson, Managing Director of Elastomer Products, about the experiences of businesses in the aftermath of the 2010 and 2011 Canterbury earthquakes. Thomson talks about the importance of focussing on people, diversifying infrastructure, and informing customers after the earthquakes. He also talks about the need for businesses to understand their insurance policies and to have building and service fall-back plans. This video is part of a series about businesses in Christchurch after the earthquakes.

Audio, Radio New Zealand

Base isolation has generally been considered an expensive system used mainly in commercial buildings to make them more earthquake resilient. Katy Gosset meets the University of Canterbury engineers who've developed a safe, low cost model that could work in our homes.

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.

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.

Images, UC QuakeStudies

A digitally manipulated image of a broken window on Spicer House. The photographer comments, "One of the office blocks in Christchurch City, New Zealand. As the window has not been fixed I am presuming that this building will be slowly demolished at a later date".