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Research Papers, Lincoln University

As a result of the findings and recommendations of the Royal Commission of Inquiry into the Canterbury Earthquake Swarm of 2010-2011 the New Zealand Government has introduced new legislation that will require the mandatory strengthening of all earthquake-prone buildings in New Zealand. An earthquake prone building is currently defined as a building that is less than one third the seismic strength of a new building. If an owner does not wish to strengthen their buildings then they must demolish them. Seismic retrofitting of buildings is a form of property development and as such, the decision to retrofit or not should be based on a robust and soundly conducted feasibility study. Feasibility studies on seismic retrofitting can be particularly challenging for a number of reasons thus making it difficult for owners to make informed and sound decisions relating to their earthquake prone buildings. This paper considers the concept and process of feasibility analysis as applied to earthquake prone buildings and discusses the current challenges posed by such feasibility studies. A number of recommendations are made in an attempt to help develop a best practice model for decision making relating to earthquake prone buildings."

Research papers, University of Canterbury Library

© 2017 The Royal Society of New Zealand. This paper discusses simulated ground motion intensity, and its underlying modelling assumptions, for great earthquakes on the Alpine Fault. The simulations utilise the latest understanding of wave propagation physics, kinematic earthquake rupture descriptions and the three-dimensional nature of the Earth's crust in the South Island of New Zealand. The effect of hypocentre location is explicitly examined, which is found to lead to significant differences in ground motion intensities (quantified in the form of peak ground velocity, PGV) over the northern half and southwest of the South Island. Comparison with previously adopted empirical ground motion models also illustrates that the simulations, which explicitly model rupture directivity and basin-generated surface waves, lead to notably larger PGV amplitudes than the empirical predictions in the northern half of the South Island and Canterbury. The simulations performed in this paper have been adopted, as one possible ground motion prediction, in the ‘Project AF8’ Civil Defence Emergency Management exercise scenario. The similarity of the modelled ground motion features with those observed in recent worldwide earthquakes as well as similar simulations in other regions, and the notably higher simulated amplitudes than those from empirical predictions, may warrant a re-examination of regional impact assessments for major Alpine Fault earthquakes.

Research Papers, Lincoln University

Though there is a broad consensus that communities play a key role in disaster response and recovery, most of the existing work in this area focuses on the activities of donor agencies, formal civil defence authorities, and local/central government. Consequently, there is a paucity of research addressing the on-going actions and activities undertaken by communities and ‘emergent groups’ , particularly as they develop after the immediate civil defence or ‘response’ phase is over. In an attempt to address this gap, this inventory of community-led recovery initiatives was undertaken approximately one year after the most devastating February 2011 earthquake. It is part of on-going project at Lincoln University documenting – and seeking a better understanding of - various emergent communities’ roles in recovery, their challenges, and strategies for overcoming them. This larger project also seeks to better understand how collaborative work between informal and formal recovery efforts might be facilitated at different stages of the process. This inventory was conducted over the December 2011 – February 2012 period and builds on Landcare Research’s Christchurch Earthquake Activity Inventory which was a similar snapshot taken in April 2011. The intention behind conducting this updated inventory is to gain a longitudinal perspective of how community-led recovery activities evolve over time. Each entry is ordered alphabetically and contact details have been provided where possible. A series of keywords have also been assigned that describe the main attributes of each activity to assist searches within this document.This inventory was supported by the Lincoln University Research Fund and the Royal Society Marsden Fund.

Audio, Radio New Zealand

Questions to Ministers 1. CHRIS AUCHINVOLE to the Minister of Commerce: What legislative and regulatory steps has he taken to help restore investor confidence in the financial markets? 2. Hon ANNETTE KING to the Minister for Social Development and Employment: Does she stand by her reported statement that it would be pre-emptive to rule anything out because the Government was still working its way through extensive recommendations by the Welfare Working Group? 3. TE URUROA FLAVELL to the Minister of Transport: Ka aha ia ki te whakapaipai ake i te āhua o ngā rori i te tuawhenua, he hapori Māori nei te nuinga o ngā tāngata ki reira, ā, e kiia nei e ētahi, he pērā aua rori ki ngā mea o ngā ao pōhara rawa atu? * Translation: What will he do to improve the conditions of roads in rural, predominately Māori communities, some of which have been described as of third world status? 4. Hon TREVOR MALLARD to the Prime Minister: Does he stand by his answer to Oral Question No 1 yesterday in relation to unemployed 15 to 19-year-olds, "If we look at the household labour force survey, we see that there are 26,700 people in the 15 to 19-year-old category"? 5. TIM MACINDOE to the Minister of Health: What progress are district health boards making in providing faster cancer radiation treatment for patients? 6. GRANT ROBERTSON to the Minister of Health: Are district health boards being funded sufficiently to maintain the level of services they provided in 2010/11? 7. KEVIN HAGUE to the Minister of Labour: When will the new chief inspector for mining and additional inspectors in the planned High Hazards Unit become operational? 8. CHARLES CHAUVEL to the Minister of Justice: Does he agree with the Chief Justice that the scheme for disclosure by the defence in criminal cases contained in the Criminal Procedure (Reform and Modernisation) Bill is "inconsistent with the defendant's right to have the prosecution prove its case beyond reasonable doubt" and with the late Chief District Court Judge that punishment at sentencing for procedural non-compliance "is conceptually incoherent and therefore arbitrary"? 9. Hon TAU HENARE to the Minister for Social Development and Employment: What is the Government doing to help teen parents get ahead? 10. Hon LIANNE DALZIEL to the Minister for Canterbury Earthquake Recovery: How many letters of offer from the Crown will be sent to insured residential red zone property owners this week? 11. NIKKI KAYE to the Minister of Internal Affairs: What announcements has he made today on improving flexibility for community groups receiving grants from gaming societies? 12. DARIEN FENTON to the Minister of Labour: Does she stand by her statement about making changes to mine safety that "until the royal commission of inquiry makes its findings, we will wait accordingly"?

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

This thesis addresses the topic of local bond behaviour in RC structures. The mechanism of bond refers to the composite action between deformed steel reinforcing bars and the surrounding concrete. Bond behaviour is an open research topic with a wide scope, particularly because bond it is such a fundamental concept to structural engineers. However, despite many bond-related research findings having wide applications, the primary contribution of this research is an experimental evaluation of the prominent features of local bond behaviour and the associated implications for the seismic performance of RC structures. The findings presented in this thesis attempt to address some structural engineering recommendations made by the Canterbury Earthquakes Royal Commission following the 2010-2011 Canterbury (New Zealand) earthquake sequence. A chapter of this thesis discusses the structural behaviour of flexure-dominated RC wall structures with an insufficient quantity of longitudinal reinforcement, among other in situ conditions, that causes material damage to predominantly occur at a single crack plane. In this particular case, the extent of concrete damage and bond deterioration adjacent to the crack plane will influence the ductility capacity that is effectively provided by the reinforcing steel. As a consequence of these in situ conditions, some lightly reinforced wall buildings in Christchurch lost their structural integrity due to brittle fracture of the longitudinal reinforcement. With these concerning post-earthquake observations in mind, there is the underlying intention that this thesis presents experimental evidence of bond behaviour that allows structural engineers to re-assess their confidence levels for the ability of lightly reinforced concrete structures to achieve the life-safety seismic performance objective the ultimate limit state. Three chapters of this thesis are devoted to the experimental work that was conducted as the main contribution of this research. Critical details of the experimental design, bond testing method and test programme are reported. The bond stress-slip relationship was studied through 75 bond pull-out tests. In order to measure the maximum local bond strength, all bond tests were carried out on deformed reinforcing bars that did not yield as the embedded bond length was relatively short. Bond test results have been presented in two separate chapters in which 48 monotonic bond tests and 27 cyclic bond tests are presented. Permutations of the experiments include the loading rate, cyclic loading history, concrete strength (25 to 70 MPa), concrete age, cover thickness, bar diameter (16 and 20 mm), embedded length, and position of the embedded bond region within the specimen (close or far away to the free surface). The parametric study showed that the concrete strength significantly influences the maximum bond strength and that it is reasonable to normalise the bond stress by the square-root of the concrete compressive strength, √(f'c). The generalised monotonic bond behaviour is described within. An important outcome of the research is that the measured bond strength and stiffness was higher than stated by the bond stress-slip relationship in the fib Model Code 2010. To account for these observed differences, an alternative model is proposed for the local monotonic bond stress-slip relationship. Cyclic bond tests showed a significant proportion of the total bond degradation occurs after the loading cycle in the peak bond strength range, which is when bond slip has exceeded 0.5 mm. Subsequent loading to constant slip values showed a linear relationship between the amount of bond strength degradation and the log of the number of cycles that were applied. To a greater extent, the cyclic bond deterioration depends on the bond slip range, regardless of whether the applied load cycling is half- or fully-reversed. The observed bond deterioration and hysteretic energy dissipated during cyclic loading was found to agree reasonably well between these cyclic tests with different loading protocols. The cyclic bond deterioration was also found to be reasonably consistent exponential damage models found in the literature. This research concluded that the deformed reinforcing bars used in NZ construction, embedded in moderate to high strength concrete, are able to develop high local bond stresses that are mobilised by a small amount of local bond slip. Although the relative rib geometry was not varied within this experimental programme, a general conclusion of this thesis is that deformed bars currently available in NZ have a relative rib bearing area that is comparatively higher than the test bars used in previous international research. From the parametric study it was found that the maximum monotonic bond strength is significant enhanced by dynamic loading rates. Experimental evidence of high bond strength and initial bond stiffness generally suggests that only a small amount of local bond slip that can occur when the deformed test bar was subjected to large tension forces. Minimal bond slip and bond damage limits the effective yielding length that is available for the reinforcing steel to distribute inelastic material strains. Consequently, the potential for brittle fracture of the reinforcement may be a more problematic and widespread issue than is apparent to structural engineers. This research has provided information that improve the reliability of engineering predictions (with respect to ductility capacity) of maximum crack widths and the extent of bond deterioration that might occur in RC structures during seismic actions.