The quality of public space is vital to livable cities. Yet livable cities also require empowered communities. This thesis asks: how is the landscape architect’s design expertise expressed as part of the public participation process, what are the key features of design expertise that lead to an effective design-based participation process and how does quality in the participation process relate to the quality of design outcomes? A theoretical framework is developed from which to clarify the relationship between decision-making processes in design and public participation. Insights from design theory are combined with the findings of key informant interviews with New Zealand and Northern Europe design experts, and with landscape architects, community and Council staff working in post-earthquake Ōtautahi/Christchurch, Aotearoa/New Zealand. Results of a case study of Albion Square in Ōhinehou/Lyttelton reveal that the designer’s interactions with the public play a critical role in shaping elegant design outcomes in public space design. Four key insights reveal that participatory design processes in New Zealand need to be reconsidered in order to enable landscape architects to work more closely with communities in mutual learning, rather than the currently limiting technical problem solving process. Institutional, professional and theoretical implications are drawn from the findings.
The nonlinear dynamic soil-foundation-structure interaction (SFSI) can signifi cantly affect the seismic response of buildings, causing additional deformation modes, damage and repair costs. Because of nonlinear foundation behaviour and interactions, the seismic demand on the superstructure may considerably change, and also permanent deformations at the foundation level may occur. Although SFSI effects may be benefi cial to the superstructure performance, any advantage would be of little structural value unless the phenomenon can be reliably controlled and exploited. Detrimental SFSI effects may also occur, including acceleration and displacement response ampli cation and differential settlements, which would be unconservative to neglect. The lack of proper understanding of the phenomenon and the limited available simpli ed tools accounting for SFSI have been major obstacles to the implementation of integrated design and assessment procedures into the everyday practice. In this study concepts, ideas and practical tools (inelastic spectra) for the seismic design and assessment of integrated foundation-superstructure systems are presented, with the aim to explicitly consider the impact of nonlinearities occurring at the soil-foundation interface on the building response within an integrated approach, where the foundation soil and superstructure are considered as part of an integrated system when evaluating the seismic response, working synergically for the achievement of a target global performance. A conceptual performance-based framework for the seismic design and assessment of integrated foundation-superstructure systems is developed. The framework is based on the use of peak and residual response parameters for both the superstructure and the foundation, which are then combined to produce the system performance matrix. Each performance matrix allows for worsening of the performance when different contributions are combined. An attempt is made to test the framework by using case histories from the 2011 Christchurch earthquake, which are previously shown to have been severely affected by nonlinear SFSI. The application highlights the framework sensitivity to the adopted performance limit states, which must be realistic for a reliable evaluation of the system performance. Constant ductility and constant strength inelastic spectra are generated for nonlinear SFSI systems (SDOF nonlinear superstructure and 3DOF foundation allowing for uplift and soil yielding), representing multistorey RC buildings with shallow rigid foundations supported by cohesive soils. Different ductilities/strengths, hysteretic rules (Bi-linear, Takeda and Flag-Shape), soil stiffness and strength and bearing capacity factors are considered. Footings and raft foundations are investigated, characterized respectively by constant (3 and 8) and typically large bearing capacity factors. It is confi rmed that when SFSI is considered, the superstructure yielding force needed to satisfy a target ductility for a new building changes, and that similarly, for an existing building, the ductility demand on a building of a given strength varies. The extent of change of seismic response with respect to xed-base (FB) conditions depends on the class of soils considered, and on the bearing capacity factor (SF). For SF equal to 3, the stiffer soils enhance the nonlinear rotational foundation behaviour and are associated with reduced settlement, while the softer ones are associated with increased settlement response but not signi ficant rotational behaviour. On average terms, for the simplifi ed models considered, SFSI is found to be bene cial to the superstructure performance in terms of acceleration and superstructure displacement demand, although exceptions are recorded due to ground motion variability. Conversely, in terms of total displacement, a signi cant response increase is observed. The larger the bearing capacity factor, the more the SFSI response approaches the FB system. For raft foundation buildings, characterized by large bearing capacity factors, the impact of foundation response is mostly elastic, and the system on average approaches FB conditions. Well de fined displacement participation factors to the peak total lateral displacement are observed for the different contributions (i.e. peak foundation rotation and translation and superstructure displacement). While the superstructure and foundation rotation show compensating trends, the foundation translation contribution varies as a function of the moment-to-shear ratio, becoming negligible in the medium-to-long periods. The longer the superstructure FB period, the less the foundation response is signifi cant. The larger the excitation level and the less ductile the superstructure, the larger the foundation contribution to the total lateral displacement, and the less the superstructure contribution. In terms of hysteretic behaviour, its impact is larger when the superstructure response is more signifi cant, i.e. for the softer/weaker soils and larger ductilities. Particularly, for the Flag Shape rule, larger superstructure displacement participation factors and smaller foundation contributions are recorded. In terms of residual displacements, the total residual-to-maximum ratios are similar in amplitudes and trends to the corresponding FB system responses, with the foundation and superstructure contributions showing complementary trends. The impact of nonlinear SFSI is especially important for the Flag Shape hysteresis rule, which would not otherwise suffer of any permanent deformations. By using the generated peak and residual inelastic spectra (i.e. inelastic acceleration/ displacement modifi cation factor spectra, and/or participation factor and residual spectra), conceptual simplifi ed procedures for the seismic design and assessment of integrated foundation-superstructure systems are presented. The residual displacements at both the superstructure and foundation levels are explicitly considered. Both the force- and displacement-based approaches are explored. The procedures are de fined to be complementary to the previously proposed integrated performance-based framework. The use of participation factor spectra allows the designer to easily visualize the response of the system components, and could assist the decision making process of both the design and assessment of SFSI systems. The presented numerical results have been obtained using simpli ed models, assuming rigid foundation behaviour and neglecting P-Delta effects. The consideration of more complex systems including asymmetry in stiffness, mass, axial load and ground conditions with a exible foundation layout would highlight detrimental SFSI effects as related to induced differential settlements, while accounting for PDelta effects would further amplify the displacement response. Also, the adopted acceleration records were selected and scaled to match conventional design spectra, thus not representing any response ampli cation in the medium-to-long period range which could as well cause detrimental SFSI effects. While these limitations should be the subject of further research, this study makes a step forward to the understanding of SFSI phenomenon and its incorporation into performance-based design/assessment considerations.
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© 2018 Springer Nature B.V. This study compares seismic losses considering initial construction costs and direct-repair costs for New Zealand steel moment-resisting frame buildings with friction connections and those with extended bolted-end-plate connections. A total of 12 buildings have been designed and analysed considering both connection types, two building heights (4-storey and 12-storey), and three locations around New Zealand (Auckland, Christchurch, and Wellington). It was found that buildings with friction connections required design to a higher design ductility, yet are generally stiffer due to larger beams being required to satisfy higher connection overstrength requirements. This resulted in the frames with friction connections experiencing lower interstorey drifts on most floors but similar peak total floor accelerations, and subsequently incurring lower drift-related seismic repair losses. Frames with friction connections tended to have lower expected net-present-costs within 50 years of the building being in service for shorter buildings and/or if located in regions of high seismicity. None of the frames with friction connections in Auckland showed any benefits due to the low seismicity of the region.
Creativity that is driven by a need for physical or economic survival, which disasters are likely to inspire, raises the question of whether such creativity fits with conventional theories and perspectives of creativity. In this paper we use the opportunity afforded by the 2010-2013 Christchurch, New Zealand earthquakes to follow and assess the creative practices and responses of a number of groups and individuals. We use in-depth interviews to tease out motivations and read these against a range of theoretical propositions about creativity. In particular, we focus on the construct of “elite panic” and the degree to which this appeared to be evident in the Christchurch earthquakes context. Bureaucratic attempts to control or limit creativity were present but they did not produce a completely blanket dampening effect. Certain individuals and groups seemed to be pre-equipped to navigate or ignore potential blocks to creativity. We argue, using Geir Kaufmann’s novelty-creativity matrix and aspects of Teresa Amabile’s and Michael G. Pratt’s revised componential theory of creativity that a special form of disaster creativity does exist.
Welcome to the Recover newsletter Issue 2 from the Marine Ecology Research Group (MERG) at the University of Canterbury. Recover is designed to keep you updated on our MBIE funded earthquake recovery project called RECOVER (Reef Ecology, Coastal Values & Earthquake Recovery). This second issue profiles some of the recent work done by our team out in the field!
Observations made in past earthquakes, in New Zealand and around the world, have highlighted the vulnerability of non-structural elements such as facades, ceilings, partitions and services. Damage to these elements can be life-threatening or jeopardise egress routes but typically, the main concern is the cost and time associated with repair works. The Insurance Council of New Zealand highlighted the substantial economic losses in recent earthquakes due to poor performance of non-structural elements. Previous inspections and research have attributed the damage to non-structural elements principally to poor coordination, inadequate or lack of seismic restraints and insufficient clearances to cater for seismic actions. Secondary issues of design responsibility, procurement and the need for better alignment of the various Standards have been identified. In addition to the compliance issues, researchers have also demonstrated that current code provisions for non-structural elements, both in New Zealand and abroad, may be inadequate. This paper first reviews the damage observed against the requirements of relevant Standards and the New Zealand Building Code, and it appears that, had the installations been compliant, the cost of repair and business interruption would have been substantially less. The second part of the paper highlights some of the apparent shortcomings with the current design process for non-structural elements, points towards possible alternative strategies and identifies areas where more research is deemed necessary. The challenge of improving the seismic performance of non-structural elements is a complex one across a diverse construction industry. Indications are that the New Zealand construction industry needs to completely rethink the delivery approach to ensure an integrated design, construction and certification process. The industry, QuakeCentre, QuakeCoRE and the University of Canterbury are presently working together to progress solutions. Indications are that if new processes can be initiated, better performance during earthquakes will be achieved while delivering enhanced building and business resilience.
<b>In the late 1960s the Wellington City Council surveyed all the commercial buildings in the city and marked nearly 200 as earthquake prone. The owners were given 15 years to either strengthen or demolish their buildings. The end result was mass demolition throughout the seventies and eighties.¹ Prompted by the Christchurch earthquakes, once again the council has published a list of over 630 earthquake prone buildings that need to be strengthened or demolished by 2030.²Of these earthquake prone buildings, the majority were built between 1880 and 1930, with 125 buildings appearing on the Wellington City Council Heritage Building List.³ This list accounts for a significant proportion of character buildings in the city. There is a danger that the aesthetic integrity of our city will be further damaged due to the urgent need to strengthen these buildings. Many of the building owners are resistant because of the high cost. By adapting these buildings to house co-workspaces, we can gain more than just the retention of the building’s heritage. The seismic upgrade provides the opportunity for the office space to be redesigned to suit changes in the ways we work. Through a design-based research approach this thesis proposes a framework that clarifies the process of adapting Wellington’s earthquake prone heritage buildings to accommodate co-working. This framework deals with the key concepts of program, structure and heritage. The framework is tested on one of Wellington’s earthquake prone heritage buildings, the Wellington Working Men’s Club, in order to demonstrate what can be gained from this strengthening process. ¹ Reid, J., “Hometown Boomtown,” in NZ On Screen (Wellington, 1983).</b>
² Wellington City Council, List of Earthquake Prone Buildings as at 06/03/2017. (Wellington: Absolutely Positively Wellington. 2017).
³ ibid.
Welcome to the first Recover newsletter from the Marine Ecology Research Group (MERG) at the University of Canterbury. Recover is designed to keep you updated on our MBIE funded earthquake recovery project called RECOVER (Reef Ecology, Coastal Values & Ecosystem Recovery). This first issue provides a summary of some of the big changes we’ve seen. In the next issue we’ll be profiling some of the current research as well as ways you can get involved!
This thesis presents the findings from an experimental programme to determine the performance and behaviour of an integrated building incorporating low damage structural and non-structural systems. The systems investigated included post-tensioned rocking concrete frames, articulated floor solutions, low damage claddings and low damage partition systems. As part of a more general aim to increase the resilience of society against earthquake hazards, more emphasis has been given to damage-control design approaches in research. Multiple low-damage earthquake resistant structural and non-structural systems have emerged that are able to withstand high levels of drift or deflections will little or negligible residual. Dry jointed connections, articulated floor solutions, low damage cladding systems and low damage drywall partitions have all been developed separately and successfully tested. In spite of the extensive research effort and the adoption in practice of the low damage systems, work was required to integrate the systems within one building and verify the constructibility, behaviour and performance of the integrated systems. The objectives of this research were to perform dynamic experimental testing of a building which incorporated the low damage systems and acquire data which could be used to dynamically validate numerical models for each of the systems. A three phase experimental programme was devised and performed to dynamically test a half-scale two storey reinforced concrete building on the University of Canterbury shaking table. The three phases of the programme investigated: The structural system only. The rocking connections were tested as Post-Tensioned only connections and Hybrid connections (including dissipators). Two different articulated floor connections were also investigated. Non-structural systems. The Hybrid building was tested with each non-structural system separately; including low damage claddings, low damage partitions and traditional partitions. The Complete building was tested with Hybrid connections, low damage claddings and low damage partitions all integrated within the test specimen. The building was designed based on a full scale prototype building following the direct displacement based design to reach a peak inter-storey drift of 1.6% in a 1/500 year ground motion for a Wellington site. For each test set up, the test specimen was subjected to a ground motion sequence of 39 single direction ground motions. Through the sequence, both the local and global behaviours of the building and integrated systems were recorded in real time. The test specimen was subjected to over 400 ground motions throughout the testing programme. It sustained no significant damage that required reparations other than crumbling of the grout pads. The average peak inter-storey drifts of the buildings were lower than the design value of 1.6%. The low damage non-structural elements were undamaged in the ground motion sequence. The data acquired from each of the phases was used to successfully validate numerical models for each of the low damage systems included in the research.
Natural catastrophes are increasing worldwide. They are becoming more frequent but also more severe and impactful on our built environment leading to extensive damage and losses. Earthquake events account for the smallest part of natural events; nevertheless seismic damage led to the most fatalities and significant losses over the period 1981-2016 (Munich Re). Damage prediction is helpful for emergency management and the development of earthquake risk mitigation projects. Recent design efforts focused on the application of performance-based design engineering where damage estimation methodologies use fragility and vulnerability functions. However, the approach does not explicitly specify the essential criteria leading to economic losses. There is thus a need for an improved methodology that finds the critical building elements related to significant losses. The here presented methodology uses data science techniques to identify key building features that contribute to the bulk of losses. It uses empirical data collected on site during earthquake reconnaissance mission to train a machine learning model that can further be used for the estimation of building damage post-earthquake. The first model is developed for Christchurch. Empirical building damage data from the 2010-2011 earthquake events is analysed to find the building features that contributed the most to damage. Once processed, the data is used to train a machine-learning model that can be applied to estimate losses in future earthquake events.
Natural hazard reviews reveal increases in disaster impacts nowhere more pronounced than in coastal settlements. Despite efforts to enhance hazard resilience, the common trend remains to keep producing disaster prone places. This paper explicitly explores hazard versus multi-hazard concepts to illustrate how different conceptualizations can enhance or reduce settlement resilience. Understandings gained were combined with onthe-ground lessons from earthquake and flooding experiences to develop of a novel ‘first cut’ approach for analyzing key multi-hazard interconnections, and to evaluate resilience enhancing opportunities. Traditional disaster resilience efforts often consider different hazard types discretely. However, recent events in Christchurch, a New Zealand city that is part of the 100 Resilient Cities network, highlight the need to analyze the interrelated nature of different hazards, especially for enhancing lifelines system resilience. Our overview of the Christchurch case study demonstrates that seismic, hydrological, shallow-earth, and coastal hazards can be fundamentally interconnected, with catastrophic results where such interconnections go unrecognized. In response, we have begun to develop a simple approach for use by different stakeholders to support resilience planning, pre and post disaster, by: drawing attention to natural and built environment multi-hazard links in general; illustrating a ‘first cut’ tool for uncovering earthquake-flooding multi-hazard links in particular; and providing a basis for reviewing resilience strategy effectiveness in multi-hazard prone environments. This framework has particular application to tectonically active areas exposed to climate-change issues.
A review of the literature showed the lack of a truly effective damage avoidance solution for timber or hybrid timber moment resisting frames (MRFs). Full system damage avoidance selfcentring behaviour is difficult to achieve with existing systems due to damage to the floor slab caused by beam-elongation. A novel gravity rocking, self-centring beam-column joint with inherent and supplemental friction energy dissipation is proposed for low-medium rise buildings in all seismic zones where earthquake actions are greater than wind. Steel columns and timber beams are used in the hybrid MRF such that both the beam and column are continuous thus avoiding beam-elongation altogether. Corbels on the columns support the beams and generate resistance and self-centring through rocking under the influence of gravity. Supplemental friction sliders at the top of the beams resist sliding of the floor whilst dissipating energy as the floor lifts on the corbels and returns. 1:20 scale tests of 3-storey one-by-two bay building based on an earlier iteration of the proposed concept served as proof-of-concept and highlighted areas for improvement. A 1:5 scale 3-storey one-by-one bay building was subsequently designed. Sub-assembly tests of the beam-top asymmetric friction sliders demonstrated repeatable hysteresis. Quasi-static tests of the full building demonstrated a ‘flat bottomed’ flag-shaped hysteresis. Shake table tests to a suite of seven earthquakes scaled for Wellington with site soil type D to the serviceability limit state (SLS), ultimate limit state (ULS) and maximum credible event (MCE) intensity corresponding to an average return period of 25, 500 and 2500 years respectively were conducted. Additional earthquake records from the 22 February 2011 Christchurch earthquakes we included. A peak drift of 0.6%, 2.5% and 3.8% was reached for the worst SLS, ULS and MCE earthquake respectively whereas a peak drift of 4.5% was reached for the worst Christchurch record for tests in the plane of the MRF. Bi-directional tests were also conducted with the building oriented at 45 degrees on the shake table and the excitation factored by 1.41 to maintain the component in the direction of the MRF. Shear walls with friction slider hold-downs which reached similar drifts to the MRF were provided in the orthogonal direction. Similar peak drifts were reached by the MRF in the bi-directional tests, when the excitation was amplified as intended. The building self-centred with a maximum residual drift of 0.06% in the dynamic tests and demonstrated no significant damage. The member actions were magnified by up to 100% due to impact upon return of the floor after uplift when the peak drift reached 4.5%. Nonetheless, all of the members and connections remained essentially linearelastic. The shake table was able to produce a limited peak velocity of 0.275 m/s and this limited the severity of several of the ULS, MCE and Christchurch earthquakes, especially the near-field records with a large velocity pulse. The full earthquakes with uncapped velocity were simulated in a numerical model developed in SAP2000. The corbel supports were modelled with the friction isolator link element and the top sliders were modelled with a multi-linear plastic link element in parallel with a friction spring damper. The friction spring damper simulated the increase in resistance with increasing joint rotation and a near zero return stiffness, as exhibited by the 1:5 scale test building. A good match was achieved between the test quasi-static global force-displacement response and the numerical model, except a less flat unloading curve in the numerical model. The peak drift from the shake table tests also matched well. Simulations were also run for the full velocity earthquakes, including vertical ground acceleration and different floor imposed load scenarios. Excessive drift was predicted by the numerical model for the full velocity near-field earthquakes at the MCE intensity and a rubber stiffener for increasing the post joint-opening stiffness was found to limit the drift to 4.8%. Vertical ground acceleration had little effect on the global response. The system generates most of its lateral resistance from the floor weight, therefore increasing the floor imposed load increased the peak drift, but less than it would if the resistance of the system did not increase due to the additional floor load. A seismic design procedure was discussed under the framework of the existing direct displacement-based design method. An expression for calculating the area-based equivalent viscous damping (EVD) was derived and a conservative correction factor of 0.8 was suggested. A high EVD of up to about 15% can be achieved with the proposed system at high displacement ductility levels if the resistance of the top friction sliders is maximised without compromising reliable return of the floor after uplift. Uniform strength joints with an equal corbel length up the height of the building and similar inter-storey drifts result in minimal relative inter-floor uplift, except between the first floor and ground. Guidelines for detailing the joint for damage avoidance including bi-directional movement were also developed.
This research investigates the validation of simulated ground motions on complex structural systems. In this study, the seismic responses of two buildings are compared when they are subjected to as-recorded ground motions and simulated ones. The buildings have been designed based on New Zealand codes and physically constructed in Christchurch, New Zealand. The recorded ground motions are selected from 40 stations database of the historical 22 Feb. 2011 Christchurch earthquake. The Graves and Pitarka (2015) methodology is used to generate the simulated ground motions. The geometric mean of maximum inter-story drift and peak floor acceleration are selected as the main seismic responses. Also, the variation of these parameters due to record to record variability are investigated. Moreover, statistical hypothesis testing is used to investigate the similarity of results between observed and simulated ground motions. The results indicate a general agreement between the peak floor acceleration calculated by simulated and recorded ground motions for two buildings. While according to the hypothesis tests result, the difference in drift can be significant for the building with a shorter period. The results will help engineers and researchers to use or revise the procedure by using simulated ground motions for obtaining seismic responses.
Following the recent earthquakes in Chile (2010) and New Zealand (2010/2011), peculiar failure modes were observed in Reinforced Concrete (RC) walls. These observations have raised a global concern on the contribution of bi-directional loading to these failure mechanisms. One of the failure modes that could potentially result from bidirectional excitations is out-of-plane shear failure. In this paper an overview of the recent experimental and numerical findings regarding out-of-plane shear failure in RC walls are presented. The numerical study presents the Finite Element (FE) simulation of wall D5-6 from the Grand Chancellor Hotel that failed in shear in the out-of-plane direction in the February 2011 Christchurch earthquake. The main objective of the numerical study was to investigate the reasons for this failure mode. The experimental campaign includes the recent experiments conducted in the Structural Engineering Laboratory of the University of Canterbury. The experimental study included three rectangular slender RC walls designed based on NZS3101: 2006-A3 (2017) for three different ductility levels, namely: nominally ductile, limited ductile and ductile. The numerical results showed that high axial load combined with bi-directional loading caused the out-of-plane shear failure in wall D5-6 from the Grand Chancellor Hotel. This was also confirmed and further investigated in the experimental phase of the study.
Background: Earthquakes are found to have lingering post-disaster effects on children that can be present for months or years after the disaster, including hyperarousal symptoms. Young children have the most difficulties in regulating their emotions, especially when they are highly aroused. Colouring-in mandala designs have been found to reduce hyperarousal symptoms of stress in young adults. The purpose of this study was to determine if the same effects of colouring-in mandalas would be seen with children showing signs of hyperarousal. Research Question: To identify what effect colouring-in mandala designs would have on the heart rate in a young child showing signs of hyperarousal. Method: Following approved procedures for informed consent, two 6-year-old girls from a Christchurch primary school were chosen for the study. Heart rate was measured using a Fitbit in a single subject design. The baseline, colouring-in and a second baseline phase were conducted during mathematics. The participants and their teacher reported on arousal, enjoyment, and positive and problem behaviours. The study took 26 school days to complete. Results: Compared with baseline, the average heart rate data showed no decrease in heart rate (i.e., calming effect) during the mandala colouring-in task phase. Conclusions: The participants enjoyed colouring-in the mandalas, but the average heart rate data did not show that colouring-in pre-drawn designs reduced heart rate, a measure of arousal. Major study limitations included; not having suitable participants or a suitable setting for the colouring-in task, and not being able to observe both participants.
Following the 2010/2011 Canterbury (New Zealand) earthquakes the seismic design of buildings with precast concrete panels has received significant attention. Although this form of construction generally performed adequately in Christchurch, there were a considerable number of precast concrete panel connection failures. This observation prompted a review of more than 4700 panel details to establish representative details used in both existing and new multi-storey and low rise industrial precast concrete buildings. The detailing and quantity of each reviewed connection type in the sampled data is reported, and advantages and potential deficiencies of each connection type are discussed. Following the Canterbury earthquakes, it was observed that brittle failure had occurred in some grouted metal duct connections used for precast concrete wall panels, resulting in recommendations for more robust detailing of this connection type. A set of experimental tests was subsequently performed to investigate the in-plane seismic behaviour of precast concrete wall panel connections. This testing comprised of seven reversed cyclic in-plane tests of fullscale precast concrete wall panels having wall-to-foundation grouted metal duct connections. Walls with existing connection detailing were found to perform adequately when carrying low axial loads, but performance was found to be less satisfactory as the axial load and wall panel length increased. The use of new recommended detailing was observed to prevent brittle connection response and to improve the robustness of the reinforcement splice. A parametric investigation was conducted using the finite element method to predict the failure mode of metal duct connections. From the results of the parametric study on metal duct connections it was identified that there were three possible failure modes, being reinforcement fracture, concrete spalling without metal duct pull out, and concrete spalling with metal duct pull-out. An alternative simple analytical method was proposed in order to determine the type of connection failure without using a time-consuming finite element method. Grouted sleeves inserts are an alternative connector that is widely used to connect wall panels to the foundations. The two full-scale wall panels were subjected to reversed cyclic in-plane demands until failure of either the connection or the wall panel. Wall panel failure was due to a combination of connection reinforcement pulling-out from the coupler and reinforcement fracture. In addition, non-embedded grouted sleeve tests filled with different quality of grout were conducted by subjecting these coupler assemblages to cyclic and monotonic forces.
Following a natural disaster, children are prone to various reactions and maladaptive responses as a result of exposure to a highly stressful and potentially traumatic event. Children’s responses can range from an acute stress response to post-traumatic-stress disorder or may fall somewhere in between. While responses to highly stressful events vary, a common finding is that children will develop sleep problems. This was found following the Christchurch September 2010 and February 2011 earthquakes. The purpose of this study was to investigate the context and phenomenology of the sleep problems of a small number of children experiencing these and the 2016 Kaikoura earthquakes, including possible mechanisms of effect. Participants were four families, including four mothers, one father and four children. The design of this study was unique. Interview data was subjected to a content analysis, extracted themes were organised according to an ecological-transactional framework and then the factors were subject to an analysis, based on the principles of clinical reasoning, in order to identify possible mechanisms of effect. Parents reported 16 different sleep problems across children, as well as other behaviours possibly indicative of post-traumatic stress response. In total, 34 themes and 26 interactions were extracted in relation to factors identified across participants about the children’s sleep and the families’ earthquake experiences. This demonstrated how complex it is to explore the development of sleep problems in the context of disaster. Key factors identified by parents that likely played a key role in the development and perpetuation of sleep problems included earthquake related anxiety, parental mental health and conflict, the child’s emotional and behavioural problems and other negative life events following the earthquakes. The clinical implications of the analysis included being aware that such families, may not have had access to specialized support around their children’s sleep. This was much needed due to the strain such problems place on the family, especially in a post-disaster community such as Christchurch.
Reinforced concrete buildings that satisfied modern seismic design criteria generally behaved as expected during the recent Canterbury and Kaikoura earthquakes in New Zealand, forming plastic hinges in intended locations. While this meant that life-safety performance objectives were met, widespread demolition and heavy economic losses took place in the aftermath of the earthquakes.The Christchurch central business district was particularly hard hit, with over 60% of the multistorey reinforced concrete buildings being demolished. A lack of knowledge on the post-earthquake residual capacity of reinforced concrete buildings was a contributing factor to the mass demolition.Many aspects related to the assessment of earthquake-damaged reinforced concrete buildings require further research. This thesis focusses on improving the state of knowledge on the post earthquakeresidual capacity and reparability of moderately damaged plastic hinges, with an emphasis on plastic hinges typical of modern moment frame structures. The repair method focussed on is epoxy injection of cracks and patching of spalled concrete. A targeted test program on seventeen nominally identical large-scale ductile reinforced concrete beams, three of which were repaired by epoxy injection following initial damaging loadings, was conducted to support these objectives. Test variables included the loading protocol, the loading rate, and the level of restraint to axial elongation.The information that can be gleaned from post-earthquake damage surveys is investigated. It is shown that residual crack widths are dependent on residual deformations, and are not necessarily indicative of the maximum rotation demands or the plastic hinge residual capacity. The implications of various other types of damage typical of beam and column plastic hinges are also discussed.Experimental data are used to demonstrate that the strength and deformation capacity of plastic hinges with modern seismic detailing are often unreduced as a result of moderate earthquake induced damage, albeit with certain exceptions. Special attention is given to the effects of prior yielding of the longitudinal reinforcement, accounting for the low-cycle fatigue and strain ageing phenomena. A material-level testing program on the low-cycle fatigue behaviour of grade 300E reinforcing steel was conducted to supplement the data available in the literature.A reduction in stiffness, relative to the initial secant stiffness to yield, occurs due to moderate plastic hinging damage. This reduction in stiffness is shown to be correlated with the ductility demand,and a proposed model gives a conservative lower-bound estimate of the residual stiffness following an arbitrary earthquake-type loading. Repair by epoxy injection is shown to be effective in restoring the majority of stiffness to plastic hinges in beams. Epoxy injection is also shown to have implications for the residual strength and elongation characteristics of repaired plastic hinges.
One of the most controversial issues highlighted by the 2010-2011 Christchurch earthquake series and more recently the 2016 Kaikoura earthquake, has been the evident difficulty and lack of knowledge and guidelines for: a) evaluation of the residual capacity damaged buildings to sustain future aftershocks; b) selection and implementation of a series of reliable repairing techniques to bring back the structure to a condition substantially the same as prior to the earthquake; and c) predicting the cost (or cost-effectiveness) of such repair intervention, when compared to fully replacement costs while accounting for potential aftershocks in the near future. As a result of such complexity and uncertainty (i.e., risk), in combination with the possibility (unique in New Zealand when compared to most of the seismic-prone countries) to rely on financial support from the insurance companies, many modern buildings, in a number exceeding typical expectations from past experiences at an international level, have ended up being demolished. This has resulted in additional time and indirect losses prior to the full reconstruction, as well as in an increase in uncertainty on the actual relocation of the investment. This research project provides the main end-users and stakeholders (practitioner engineers, owners, local and government authorities, insurers, and regulatory agencies) with comprehensive evidence-based information to assess the residual capacity of damage reinforced concrete buildings, and to evaluate the feasibility of repairing techniques, in order to support their delicate decision-making process of repair vs. demolition or replacement. Literature review on effectiveness of epoxy injection repairs, as well as experimental tests on full-scale beam-column joints shows that repaired specimens have a reduced initial stiffness compared with the undamaged specimen, with no apparent strength reduction, sometimes exhibiting higher displacement ductility capacities. Although the bond between the steel and concrete is only partially restored, it still allows the repaired specimen to dissipate at least the same amount of hysteretic energy. Experimental tests on buildings subjected to earthquake loading demonstrate that even for severe damage levels, the ability of the epoxy injection to restore the initial stiffness of the structure is significant. Literature review on damage assessment and repair guidelines suggests that there is consensus within the international community that concrete elements with cracks less than 0.2 mm wide only require cosmetic repairs; epoxy injection repairs of cracks less and 2.0 mm wide and concrete patching of spalled cover concrete (i.e., minor to moderate damage) is an appropiate repair strategy; and for severe damaged components (e.g., cracks greater than 2.0 mm wide, crushing of the concrete core, buckling of the longitudinal reinforcement) local replacement of steel and/or concrete in addition to epoxy crack injection is more appropriate. In terms of expected cracking patterns, non-linear finite element investigations on well-designed reinforced concrete beam-to-column joints, have shown that lower number of cracks but with wider openings are expected to occur for larger compressive concrete strength, f’c, and lower reinforcement content, ρs. It was also observed that the tensile concrete strength, ft, strongly affects the expected cracking pattern in the beam-column joints, the latter being more uniformly distributed for lower ft values. Strain rate effects do not seem to play an important role on the cracking pattern. However, small variations in the cracking pattern were observed for low reinforcement content as it approaches to the minimum required as per NZS 3101:2006. Simple equations are proposed in this research project to relate the maximum and residual crack widths with the steel strain at peak displacement, with or without axial load. A literature review on fracture of reinforcing steel due to low-cycle fatigue, including recent research using steel manufactured per New Zealand standards is also presented. Experimental results describing the influence of the cyclic effect on the ultimate strain capacity of the steel are also discussed, and preliminary equations to account for that effect are proposed. A literature review on the current practice to assess the seismic residual capacity of structures is also presented. The various factors affecting the residual fatigue life at a component level (i.e., plastic hinge) of well-designed reinforced concrete frames are discussed, and equations to quantify each of them are proposed, as well as a methodology to incorporate them into a full displacement-based procedure for pre-earthquake and post-earthquake seismic assessment.
This research examines the connection between accessibility and resilience in post-earthquake Christchurch. This research will provide my community partner with a useful evidence base to help show that increased accessibility does create a more resilient environment. This research uses an in-depth literature review along with qualitative interview approach discussing current levels of accessibility and resilience in Christchurch and whether or not the interview participants believe that increased accessibility in Christchurch will make our city more resilient to future disasters. This research is important because it helps to bridge the connection between accessibility and resilience by showing how accessibility is an important aspect of making a city resilient. In Christchurch specifically, it is a great time to create an accessible and inclusive environment in the post-earthquake rebuild state the city is currently in. Showing that an accessible environment will lead to a more resilient city is important will potentially lead to accessible design being included in the rebuild of places and spaces in Christchurch. In theory, the results of this research show that having an accessible environment leads to universal inclusiveness which in turn, leads to a resilient city. An overarching theme that arose during this research is that accessibility is a means to inclusion and without inclusion a society cannot be resilient. In practice, the results show that for Christchurch to become more accessible and inclusive for people with disabilities, there needs to not only be an increase the accessibility of places and spaces but accessibility to the community as well. Having accessible infrastructure and communities will lead to increased social and urban resilience, especially for individuals with disabilities. This research is beneficial because it helps to bridge the connection between accessibility and resilience. Resilience is important because it help cities prepare for, respond to and recover from disasters and this research helps to show that accessibility is an important part of creating resilience. Some questions still remain unresolved mainly looking into normalising accessibility and deciphering how to prove that accessibility is an issue that effects everybody, not just individuals with disabilities.
This research examines the connection between accessibility and resilience in post-earthquake Christchurch. This research will provide my community partner with a useful evidence base to help show that increased accessibility does create a more resilient environment. This research uses an in-depth literature review along with qualitative interview approach discussing current levels of accessibility and resilience in Christchurch and whether or not the interview participants believe that increased accessibility in Christchurch will make our city more resilient to future disasters. This research is important because it helps to bridge the connection between accessibility and resilience by showing how accessibility is an important aspect of making a city resilient. In Christchurch specifically, it is a great time to create an accessible and inclusive environment in the post-earthquake rebuild state the city is currently in. Showing that an accessible environment will lead to a more resilient city is important will potentially lead to accessible design being included in the rebuild of places and spaces in Christchurch. In theory, the results of this research show that having an accessible environment leads to universal inclusiveness which in turn, leads to a resilient city. An overarching theme that arose during this research is that accessibility is a means to inclusion and without inclusion a society cannot be resilient. In practice, the results show that for Christchurch to become more accessible and inclusive for people with disabilities, there needs to not only be an increase the accessibility of places and spaces but accessibility to the community as well. Having accessible infrastructure and communities will lead to increased social and urban resilience, especially for individuals with disabilities. This research is beneficial because it helps to bridge the connection between accessibility and resilience. Resilience is important because it help cities prepare for, respond to and recover from disasters and this research helps to show that accessibility is an important part of creating resilience. Some questions still remain unresolved mainly looking into normalising accessibility and deciphering how to prove that accessibility is an issue that effects everybody, not just individuals with disabilities.
Background: We are in a period of history where natural disasters are increasing in both frequency and severity. They are having widespread impacts on communities, especially on vulnerable communities, those most affected who have the least ability to prepare or respond to a disaster. The ability to assemble and effectively manage Interagency Emergency Response Teams (IERTs) is critical to navigating the complexity and chaos found immediately following disasters. These teams play a crucial role in the multi-sectoral, multi-agency, multi-disciplinary, and inter-organisational response and are vital to ensuring the safety and well-being of vulnerable populations such as the young, aged, and socially and medically disadvantaged in disasters. Communication is key to the smooth operation of these teams. Most studies of the communication in IERTs during a disaster have been focussed at a macro-level of examining larger scale patterns and trends within organisations. Rarely found are micro-level analyses of interpersonal communication at the critical interfaces between collaborating agencies. This study set out to understand the experiences of those working at the interagency interfaces in an IERT set up by the Canterbury District Health Board to respond to the needs of the vulnerable people in the aftermath of the destructive earthquakes that hit Canterbury, New Zealand, in 2010-11. The aim of the study was to gain insights about the complexities of interpersonal communication (micro-level) involved in interagency response coordination and to generate an improved understanding into what stabilises the interagency communication interfaces between those agencies responding to a major disaster. Methods: A qualitative case study research design was employed to investigate how interagency communication interfaces were stabilised at the micro-level (“the case”) in the aftermath of the destructive earthquakes that hit Canterbury in 2010-11 (“the context”). Participant recruitment was undertaken by mapping which agencies were involved within the IERT and approaching representatives from each of these agencies. Data was collected via individual interviews using a semi-structured interview guide and was based on the “Critical Incident Technique”. Subsequently, data was transcribed verbatim and subjected to inductive analysis. This was underpinned theoretically by Weick’s “Interpretive Approach” and supported by Nvivo qualitative data analysis software. Results: 19 participants were interviewed in this study. Out of the inductive analysis emerged two primary themes, each with several sub-factors. The first major theme was destabilising/disruptive factors of interagency communication with five sub-factors, a) conflicting role mandates, b) rigid command structures, c) disruption of established communication structures, d) lack of shared language and understanding, and e) situational awareness disruption. The second major theme stabilising/steadying factors in interagency communication had four sub-factors, a) the establishment of the IERT, b) emergent novel communication strategies, c) establishment of a liaison role and d) pre-existing networks and relationships. Finally, there was a third sub-level identified during inductive analysis, where sub-factors from both primary themes were noted to be uniquely interconnected by emergent “consequences” arising out of the disaster context. Finally, findings were synthesised into a conceptual “Model of Interagency Communication at the Micro-level” based on this case study of the Canterbury earthquake disaster response. Discussion: The three key dimensions of The People, The Connections and The Improvisations served as a framework for the discussion of what stabilises interagency communication interfaces in a major disaster. The People were key to stabilising the interagency interfaces through functioning as a flexible conduit, guiding and navigating communication at the interagency interfaces and improving situational awareness. The Connections provided the collective competence, shared decision-making and prior established relationships that stabilised the micro-level communication at interagency interfaces. And finally, The Improvisations i.e., novel ideas and inventiveness that emerge out of rapidly changing post-disaster environments, also contributed to stabilisation of micro-level communication flows across interagency interfaces in the disaster response. “Command and control” hierarchical structures do provide clear processes and structures for teams working in disasters to follow. However, improvisations and novel solutions are also needed and often emerge from first responders (who are best placed to assess the evolving needs in a disaster where there is a high degree of uncertainty). Conclusion: This study highlights the value of incorporating an interface perspective into any study that seeks to understand the processes of IERTs during disaster responses. It also strengthens the requirement for disaster management frameworks to formally plan for and to allow for the adaptive responsiveness of local teams on the ground, and legitimise and recognise the improvisations of those in the role of emergent boundary spanners in a disaster response. This needs to be in addition to existing formal disaster response mechanisms. This study provides a new conceptual model that can be used to guide future case studies exploring stability at the interfaces of other IERTs and highlights the centrality of communication in the experiences of members of teams in the aftermath of a disaster. Utilising these new perspectives on stabilising communication at the interagency interfaces in disaster responses will have practical implications in the future to better serve the needs of vulnerable people who are at greatest risk of adverse outcomes in a disaster.
The assessment of damage and remaining capacity after an earthquake is an immediate measure to determine whether a reinforced concrete (RC) building is usable and safe for occupants. The recent Christchurch earthquake (22 February 2011) caused a uniquely severe level of structural damage to modern buildings, resulting in extensive damage to the building stock. About 60% of damaged multistorey concrete buildings (3 storeys and up) were demolished after the earthquake, and the cost of reconstruction amounted to 40 billion NZD. The aftermath disclosed issues of great complexities regarding the future of the RC buildings damaged by the earthquakes. This highlighted the importance of post-event decision-making, as the outcome will allow the appropriate course of action—demolition, repair or acceptance of the existing building—to be considered. To adopt the proper strategy, accurate assessment of the residual capacity and the level of damage is required. This doctoral dissertation aims to assess the damage and remaining capacity at constituent material and member level (i.e., concrete material and beams) through a systematic approach in an attempt to address part of an existing gap in the available literature. Since the residual capacity of RC members is not unique and depends on previously applied loading history, post-event residual capacity in this study was assessed in terms of fraction of fatigue life (i.e., the number of cycles required to failure). This research comprises three main parts: (1) residual capacity and damage assessment at material level (i.e., concrete), (2) post-yield bond deterioration and damage assessment at the interface of steel and concrete, and, finally, (3) residual capacity and damage assessment at member level (i.e., RC beam). The first part of this research focused on damage assessment and the remaining capacity of concrete from a material point of view. It aimed to employ appropriate and reliable durability-based testing and image-detection techniques to quantify deterioration in the mechanical properties of concrete on the basis that stress-induced damage occurred in the microstructural system of the concrete material. To this end, in the first phase, a feasibility study was conducted in which a combination of oxygen permeability, electrical resistivity and porosity tests were assessed to determine if they were robust and reliable enough to reveal damage which occurred in the microstructural system of concrete. The results, in terms of change in permeability, electrical resistivity and porosity features of disk samples taken from the middle third of damaged concrete cylinders (200 mm × 100 mm) monotonically pre-loaded to 50%, 70%, 90% and 95% of the ultimate strength (f′c), showed the permeability test is a reliable tool to identify the degree of damage, due to its high sensitivity to the load-induced microcracking. In parallel, to determine the residual capacity, the companion damaged concrete cylinders already loaded to the same level of compressive strength were reloaded up to failure. Comparing the stress–strain relationship of damaged concrete with intact material, it was also found that the strain capacity of the reloaded pre-damaged concrete cylinders decreases while strength remained virtually unchanged. In the second phase of the first part, a fluorescent microscopy technique was used to assess the damage and develop a correlation between material degradation, by virtue of the geometrical features, and damage to the concrete. To account for the effect of confinement and cyclic loading, in the third phase, the residual capacity and damage assessment of unconfined and GFRP confined concrete cylinders subjected to low-cycle fatigue loading, was investigated. Similar to the first phase, permeability testing technique was used to provide an indirect evaluation of fatigue damage. Finally, in the fourth phase of the first part, the suitability of permeability testing technique to assess damage was evaluated for cored concrete taken from three types of RC members: columns, beams and a beam-column joint. In view of the fact that the composite action of an RC member is highly dependent on the bond between reinforcement and surrounding concrete, understanding the deterioration of the bond in the post-yield range of strain in steel was crucial to assess damage at member level. Therefore, in the second phase of this research, a state-of-the- art distributed fibre optic strain sensor system (DFOSSS) system was used to evaluate bond deterioration in a cantilever RC beam subjected to monotonic lateral loading. The technology allowed the continuous capture of strain, every 2.6 mm along the length, in both reinforcing bars and cover concrete. The strain profile provided a basis by which the slip, axial stress and bond stress distributions were then established. In the third part, the study focused on the damage assessment and residual capacity of seven half-scale RC beams subjected to a constant-amplitude cyclic loading protocol. In the first stage, the structural performances of three specimens under constant-amplitude fatigue at 1%, 2% and 4% chord rotation (drift) were examined. In parallel, the number of cycles to failure, degradation in strength, stiffness and energy dissipation were characterized. In the second stage, four RC beams were subjected to loading up to 70% and 90% of their fatigue life, at 2% and 4% drift, and then monotonically pulled up to failure. To determine the residual flexural capacity, the lateral force–displacement results of pre-damaged specimens were compared with an undamaged specimen subjected to only monotonic loading. The study showed significant losses in strength, deformability, stiffness and energy dissipation capacity. A nonlinear finite element analysis (FEA) using concrete damage plasticity (CDP) model was also conducted in ABAQUS to numerically investigate the behaviour of the tested specimen. The results of the FE simulations indicated a reasonable response compared with the behaviour of the test specimen in terms of force–displacement and cracking pattern. During the Christchurch earthquake it was observed that the loading history has a significant influence on structural responses. While in conventional pseudo-static loading protocol, internal forces can be redistributed along the plastic length: there is little chance for structures undergoing high initial loading amplitude to redistribute pertinent stresses. As a result, in the third phase of this part, the effect of high rate of loading on the behaviour of seismically designed RC beams was investigated. Two half-scale cantilever RC beams were subjected to similar constant-amplitude cyclic loading at 2% and 4% drifts, but at a rate of 500 mm/s. Due to the incapability of conventional measuring techniques, a motion-tracking system was employed for data acquisition with the high-speed tests. The effect of rate of loading on the fatigue life of specimens (i.e., the number of cycles required to failure), secant stiffness, failure mode, cracking pattern, beam elongations and bar fracture surface were analysed. Integrating the results of all parts of this research has resulted in a better understanding of residual capacity and the development of damage at both the material and member level by using a low-cycle fatigue approach.
