Describes an extensive experimental program at the University of Canterbury, for the development of new structural systems and connections for multi-storey laminated veneer lumber (LVL) timber buildings in earthquake-prone areas. The proposed innovative ductile timber connections are conceptually similar to recent seismic solutions successfully developed for precast concrete multi- storey buildings. The paper gives an overview of the research program, and the results of quasi-static cyclic tests on frame subassemblies, including exterior beam-column joints and cantilever columns, as well as pseudo-dynamic tests on cantilever columns. The experimental results showed significant dissipation of hysteretic energy, good self-centering capacity and no appreciable damage of the structural elements, confirming the expected enhanced performance of the proposed structural systems.
he 2016 Building (Earthquake Prone Building) Amendment Act aims to improve the system for managing earthquake-prone buildings. The proposed changes to the Act were precipitated by the Canterbury earthquakes, and the need to improve the seismic safety of New Zealand’s building stock. However, the Act has significant ramifications for territorial authorities, organisations and individuals in small New Zealand towns, since assessing and repairing heritage buildings poses a major cost to districts with low populations and poor rental returns on commercial buildings.
During the past two decades, the focus has been on the need to provide communities with structures that undergo minimal damage after an earthquake event while still being cost competitive. This has led to the development of high performance seismic resisting systems, and advances in design methodologies, in order respect this demand efficiently. This paper presents the experimental response of four pre-cast, post-tensioned rocking wall systems tested on the shake-table at the University of Canterbury. The wall systems were designed as a retrofit solution for an existing frame building, but are equally applicable for use in new design. Design of the wall followed a performance-based retrofit strategy in which structural limit states appropriate to both the post-tensioned wall and the existing building were considered. Dissipation for each of the four post-tensioned walls was provided via externally mounted devices, located in parallel to post-tensioned tendons for re-centring. This allowed the dissipation devices to be easily replaced or inspected following a major earthquake. Each wall was installed with viscous fluid dampers, tension-compression yielding steel dampers, a combination of both or no devices at all – thus relying on contact damping alone. The effectiveness of both velocity and displacement dependant dissipation are investigated for protection against far-field and velocity-pulse ground motion characteristics. The experimental results validate the behaviour of ‘Advanced Flag-Shape’ rocking, dissipating solutions which have been recently proposed and numerically tested. Maximum displacements and material strains were well controlled and within acceptable bounds, and residual deformations were minimal due to the re-centring contribution from the post-tensioned tendons. Damage was confined to inelastic yielding (or fluid damping) of the external dampers.
Recent major earthquakes such as Northridge 1994 and Izmit Kocaeli 1999 highlighted the poor performance of existing buildings constructed prior to the early 1970’s. Low lateral seismic design coefficients and the adopted “working stress design” methodology (essentially an elastic design) lacked any inelastic design considerations, thus leading to inadequate detailing. Insufficient development lengths, lapping within potential plastic hinge regions, lack, or total absence of joint transverse reinforcement, and the use of plain round reinforcement and hooked end anchorages were common throughout the structure. The behaviour is generally dominated by brittle local failure mechanisms (e.g. joint or element shear failures) as well as possible soft-storey mechanisms at a global level. Amongst several possible retrofit interventions, a typical solution is to provide the structure with additional structural walls i.e. external buttressing or column in-fills. Extensive developments on precast, post-tensioned, dissipative systems have shown promise for the use of rocking wall systems to retrofit existing poorly detailed frame structures. In this contribution, the feasibility of such a retrofit intervention is investigated. A displacement-based retrofit procedure is developed and proposed, based on targeting pre-defined performance criteria, such as joint shear and/or column curvature deformation limits. A design example, using the proposed retrofit strategy on a prototype frame is presented. A brief overview on experimental work ongoing at the University of Canterbury investigating the dynamic response of advanced rocking walls for retrofit purposes will be provided.
It is fast becoming common practice for civil engineering infrastructure and building structures to be designed to achieve a set of performance objectives. To do so, consideration is now being given to systems capable of sustaining minimal damage after an earthquake while still being cost competitive. This has led to the development of high performance seismic resisting systems, followed by advances in design methodologies. The paper presents the experimental response of four pre-cast, post-tensioned rocking walls with high-performing dissipating solutions tested on the shake-table at the University of Canterbury. The wall systems were designed as a retrofit solution for an existing frame building however, can also be used for the design of new, high-performance structures. The use of externally mounted dampers allowed numerous dissipation schemes to be explored including mild-steel dampers (hysteretic dampers), viscous dampers, a combination of both or no dampers. The advantages of both velocity and displacement dependant dissipation was investigated for protection against strong ground motions with differing rupture characteristics i.e. far-field and near-field events. The experimental results are used to verify a proposed design procedure for post-tensioned rocking systems with supplementary hysteretic and viscous dissipation. The predicted response compared well with the measured shake-table response.
This thesis seeks to examine how the integration of play, small toys specifically, and the use of solution-focused brief therapy techniques can affect the outcomes for primary school aged children undergoing counselling. The setting is a counselling agency in Christchurch, New Zealand. A qualitative research approach is used and the data analysed using a narrative inquiry approach. The context of this study is the counselling service of an agency where young children, adolescents and their families are helped and supported through a variety of life issues. The counselling the participants are offered uses a combination of a solution-focused and play therapy where the purpose is to encourage clients to find exceptions to their presenting problems and identify their preferred future. The aim of this study is to help the children navigate their problem through a better understanding of and the gaining of personal skills and strengths. Participants were invited to be part of this study through the agency waiting list. The four included presented with a variety of reasons for coming to counselling yet these proved similar to that which the agency has been routinely presented with in the aftermath of the Canterbury earthquakes from 2011 to present day. Each participant had the consent of their parents or caregivers to engage in this project. The participants themselves separately agreed to engage in a solution- focused counselling process where the counsellor also integrated the use of small toys as part of the course. Counselling sessions were audiotaped, aspects photographed and analysed with a specific focus on client engagement. Four key themes emerged as the participants explored their personal narrative. Firstly, the “I’m OK” theme depicted in their first scaling activity, secondly a recognition that things could indeed be better and they needed help. Thirdly, a realisation of their own strengths and skills and finally that the future was an optimistic place to look forward to. These themes are described and explained through descriptions of the participant’s stories as well as self-reflection by the researcher. Transcriptions of sessions are included as are excerpts from the research journal and photographs of the use of the small toys by the children.
Researchers have begun to explore the opportunity presented by blue-green infrastructure(a subset of nature-based solutions that provide blue and green space in urban infrastructure)as a response to the pressures of climate change. The 2010/2011 Canterbury earthquake sequence created a unique landscape within which there is opportunity to experiment with and invest in new solutions to climate change adaptation in urban centres. Constructed wetlands are an example of blue-green infrastructure that can potentially support resilience in urban communities. This research explores interactions between communities and constructed wetlands to understand how this may influence perceptions of community resilience. The regeneration of the Ōtākaro Avon River Corridor (OARC) provides a space to investigate these relationships. Seven stakeholders from the community, industry, and academia, each with experience in blue-green infrastructure in the OARC, participated in a series of semi-structured interviews. Each participant was given the opportunity to reflect on their perspectives of community, community resilience, and constructed wetlands and their interconnections. Interview questions aligned with the overarching research objectives to (1) understand perceptions around the role of wetlands in urban communities, (2) develop a definition for community resilience in the context of the Ōtākaro Avon community, and (3) reflect on how wetlands can contribute to (or detract from) community resilience. This study found that constructed wetlands can facilitate learning about the challenges and solutions needed to adapt to climate change. From the perspective of the community representatives, community resilience is linked to social capital. Strong social networks and a relationship with nature were emphasised as core components of a community’s ability to adapt to disruption. Constructed wetlands are therefore recognised as potentially contributing to community resilience by providing spaces for people to engage with each other and nature. Investment in constructed wetlands can support a wider response to climate change impacts. This research was undertaken with the support of the Ōtākaro Living Laboratory Trust, who are invested in the future of the OARC. The outcomes of this study suggest that there is an opportunity to use wetland spaces to establish programmes that explore the perceptions of constructed wetlands from a broader community definition, at each stage of the wetland life cycle, and at wider scales(e.g., at a city scale or beyond).
Christchurch Ōtautahi, New Zealand, is a city of myriad waterways and springs. Māori, the indigenous people of New Zealand, have water quality at the core of their cultural values. The city’s rivers include the Avon/Ōtākaro, central to the city centre’s aesthetic appeal since early settlement, and the Heathcote/Ōpāwaho. Both have been degraded with increasing urbanisation. The destructive earthquake sequence that occurred during 2010/11 presented an opportunity to rebuild significant areas of the city. Public consultation identified enthusiasm to rebuild a sustainable city. A sustainable water sensitive city is one where development is constructed with the water environment in mind. Water sensitive urban design applies at all scales and is a holistic concept. In Christchurch larger-scale multi-value stormwater management solutions were incorporated into rapidly developed greenfield sites on the city’s outskirts and in satellite towns, as they had been pre-earthquake. Individual properties on greenfield sites and within the city, however, continued to be constructed without water sensitive features such as rainwater tanks or living roofs. This research uses semi-structured interviews, policy analysis, and findings from local and international studies to investigate the benefits of building-scale WSUD and the barriers that have resulted in their absence. Although several inter-related barriers became apparent, cost, commonly cited as a barrier to sustainable development in general, was strongly represented. However, it is argued that the issue is one of mindset rather than cost. Solutions are proposed, based on international and national experience, that will demonstrate the benefits of adopting water sensitive urban design principles including at the building scale, and thereby build public and political support. The research is timely - there is still much development to occur, and increasing pressures from urban densification, population growth and climate change to mitigate.
New Zealand has a housing crisis. High land prices and high construction costs have all contributed to unaffordable housing. Additionally, the New Zealand dream of the "quarter acre section" lifestyle that has encouraged urban sprawl throughout our major cities with increasingly unsustainable services, transport and road costs. New and exciting housing options need to be explored for urban areas.
Christchurch is a city in New Zealand where urban sprawl has always been prevalent. In the wake of the 2010/2011 earthquakes sprawl increased further, relocating large suburban areas yet further away from the city centre. This has caused a greater reliance on cars, and a slower revival to the city.
Historically there is an aversion to higher density living. Perceived desirability is a large factor. The medium to high density solutions produced thus far have little regard for the concept of "home", with the use of substandard materials, and monotonous and repetitive design, and essentially falling short of addressing the needs of New Zealand's increasing population.
"A Home with a View" looks to address the needs of New Zealanders and Christchurch, through the individual tower-house within an overarching tower-housing neighbourhood development. The design as research thesis develops a medium density tower-housing neighbourhood as a mini city-scape, through the exploration of the tower-house as an intimate space to live and observe from.
Tower-housing has the potential to create a delightful, lively neighbourhood environment that contributes to quirky, new, and exciting housing options for New Zealand. The tower-house creates desire through unconventional lifestyle and highlights engaging solutions to an individual vertical housing type.
Current seismic retrofit strategies generally focus on increasing the strength/stiffness or upgrading the mechanical properties of a structure or element. A typical drawback of this approach is that the demand on structural and sub-structural elements can be increased. In a previous contribution by the authors (Ireland et al., 2006) a counter-intuitive but rational seismic retrofit strategy consisting of selective weakening techniques was proposed. In this paper results of experimental investigations performed on benchmark & selectively weakened structural walls at the University of Canterbury are discussed. The experimental investigations consisted of quasi-static uni-directional tests on two benchmark and two retrofitted cantilever wall specimens. The first benchmark wall specimen was detailed as typical of pre-1970’s construction practice. An equivalent wall was retrofitted using a selective weakening approach involving a horizontal cut at foundation level to allow for a controlled rocking response. The second benchmark specimen represented a more severe scenario where the inelastic behaviour was dominated by shear. A retrofit solution involving vertically segmenting the wall to improve the ductility and retain gravity carrying capacity by inducing a flexural response was implemented. The experimental results confirmed the viability and efficiency of the proposed retrofit technique towards improving the performance of structural walls. Constructability issues and suggestions for practical implementation of the proposed retrofit solution are also discussed.
The November 2016 MW 7.8 Kaikōura Earthquake initiated beneath the North Culverden basin on The Humps fault and propagated north-eastwards, rupturing at least 17 faults along a cumulative length of ~180 km. The geomorphic expression of The Humps Fault across the Emu Plains, along the NW margin of Culverden basin, comprises a series of near-parallel strands separated by up to 3 km across strike. The various strands strike east to east-northeast and have been projected to mainly dip steeply to the south in seismic data (~80°). In this area, the fault predominantly accommodates right-lateral slip, with uplift and subsidence confined to releasing and restraining bends and step-overs at a range of scales. The Kaikōura event ruptured pre-existing fault scarps along the Emu Plains, which had been partly identified prior to the earthquake. Geomorphology and faulting expression of The Humps Fault on The Emu Plains was mapped, along with faulting related structures which did not rupture in the 2016 earthquake. Fault ruptures strands are combined into sections and the kinematic deformation of sections analysed to provide a moment tensor fault plane solution. This fault plane solution is consistent with the regional principal horizontal shortening direction (PHS) of ~115°, similar to seismic focal mechanism solutions of some of the nearby aftershocks of the Kaikōura earthquake, and similar to the adjacent Hope Fault. To constrain the timing of paleoseismic events, a trench was excavated across the fault where it crossed a late Quaternary alluvial fan. Mapping of stratigraphy exposed in the trench walls, and dating of variably deformed strata, constrains the pre-historic earthquake event history at the trench site. The available data provides evidence for at least three paleo-earthquakes within the last 15.1 ka, with a possible fourth (penultimate) event. These events are estimated to have occurred at 7.7-10.3 ka, 10.3-14.8 ka, and one or more events that are older than ~15.1 ka. Some evidence suggests an additional penultimate event between 1850 C.E and 7.7 ka. Time-integrated slip-rates at three locations on the fault are measured using paleo-channels as piercing points. These sites give horizontal slip rates of 0.57 ± 0.1 mm/year, 0.49 ± 0.1 mm/year and one site constrains a minimum of between 0.1 - 0.4 mm/year. Two vertical slip-rates are calculated to be constrained to a maximum of 0.2 ± 0.02 mm/year at one site and between 0.02 and 0.1 mm/year at another site. Prior to this study, The Humps fault had only been partially documented in reconnaissance level mapping in the district, and no previous paleoseismic or slip rate data had been reported. This project has provided a detailed fault zone tectonic geomorphic map and established new slip-rate and paleoseismic data. The results highlight that The Humps fault plays an important role in regional seismicity and in accommodating plate boundary deformation across the North Canterbury region.
In most design codes, infill walls are considered as non-structural elements and thus are typically neglected in the design process. The observations made after major earthquakes (Duzce 1999, L’Aquila 2009, Christchurch 2011) have shown that even though infill walls are considered to be non-structural elements, they interact with the structural system during seismic actions. In the case of heavy infill walls (i.e. clay brick infill walls), the whole behaviour of the structure may be affected by this interaction (i.e. local or global structural failures such as soft storey mechanism). In the case of light infill walls (i.e. non-structural drywalls), this may cause significant economical losses. To consider the interaction of the structural system with the ‘non-structural ’infill walls at design stage may not be a practical approach due to the complexity of the infill wall behaviour. Therefore, the purpose of the reported research is to develop innovative technological solutions and design recommendations for low damage non-structural wall systems for seismic actions by making use of alternative approaches. Light (steel/timber framed drywalls) and heavy (unreinforced clay brick) non-structural infill wall systems were studied by following an experimental/numerical research programme. Quasi-static reverse cyclic tests were carried out by utilizing a specially designed full scale reinforced concrete frame, which can be used as a re-usable bare frame. In this frame, two RC beams and two RC columns were connected by two un-bonded post tensioning bars, emulating a jointed ductile frame system (PRESSS technology). Due to the rocking behaviour at the beam-column joint interfaces, this frame was typically a low damage structural solution, with the post-tensioning guaranteeing a linear elastic behaviour. Therefore, this frame could be repeatedly used in all of the tests carried out by changing only the infill walls within this frame. Due to the linear elastic behaviour of this structural bare frame, it was possible to extract the exact behaviour of the infill walls from the global results. In other words, the only parameter that affected the global results was given by the infill walls. For the test specimens, the existing practice of construction (as built) for both light and heavy non-structural walls was implemented. In the light of the observations taken during these tests, modified low damage construction practices were proposed and tested. In total, seven tests were carried out: 1) Bare frame , in order to confirm its linear elastic behaviour. 2) As built steel framed drywall specimen FIF1-STFD (Light) 3) As built timber framed drywall specimen FIF2-TBFD (Light) 4) As built unreinforced clay brick infill wall specimen FIF3-UCBI (Heavy) 5) Low damage steel framed drywall specimen MIF1-STFD (Light) 6) Low damage timber framed drywall specimen MIF2-TBFD (Light) 7) Low damage unreinforced clay brick infill wall specimen MIF5-UCBI (Heavy) The tests of the as built practices showed that both drywalls and unreinforced clay brick infill walls have a low serviceability inter-storey drift limit (0.2-0.3%). Based on the observations, simple modifications and details were proposed for the low damage specimens. The details proved to be working effectively in lowering the damage and increasing the serviceability drift limits. For drywalls, the proposed low damage solutions do not introduce additional cost, material or labour and they are easily applicable in real buildings. For unreinforced clay brick infill walls, a light steel sub-frame system was suggested that divides the infill panel zone into smaller individual panels, which requires additional labour and some cost. However, both systems can be engineered for seismic actions and their behaviour can be controlled by implementing the proposed details. The performance of the developed details were also confirmed by the numerical case study analyses carried out using Ruaumoko 2D on a reinforced concrete building model designed according to the NZ codes/standards. The results have confirmed that the implementation of the proposed low damage solutions is expected to significantly reduce the non-structural infill wall damage throughout a building.
The Canterbury region of New Zealand was shaken by major earthquakes on the 4th September 2010 and 22nd February 2011. The quakes caused 185 fatalities and extensive land, infrastructure and building damage, particularly in the Eastern suburbs of Christchurch city. Almost 450 ha of residential and public land was designated as a ‘Red Zone’ unsuitable for residential redevelopment because land damage was so significant, engineering solutions were uncertain, and repairs would be protracted. Subsequent demolition of all housing and infrastructure in the area has left a blank canvas of land stretching along the Avon River corridor from the CBD to the sea. Initially the Government’s official – but enormously controversial – position was that this land would be cleared and lie fallow until engineering solutions could be found that enabled residential redevelopment. This paper presents an application of a choice experiment (CE) that identified and assessed Christchurch residents’ preferences for different land use options of this Red Zone. Results demonstrated strong public support for the development of a recreational reserve comprising a unique natural environment with native fauna and flora, healthy wetlands and rivers, and recreational opportunities that align with this vision. By highlighting the value of a range of alternatives, the CE provided a platform for public participation and expanded the conversational terrain upon which redevelopment policy took place. We conclude the method has value for land use decision-making beyond the disaster recovery context.
The recent earthquakes in Christchurch have made it clear that issues exist with current RC frame design in New Zealand. In particular, beam elongation in RC frame buildings was widespread and resulted in numerous buildings being rendered irreparable. Design solutions to overcome this problem are clearly needed, and the slotted beam is one such solution. This system has a distinct advantage over other damage avoidance design systems in that it can be constructed using current industry techniques and conventional reinforcing steel. As the name suggests, the slotted beam incorporates a vertical slot along part of the beam depth at the beam-column interface. Geometric beam elongation is accommodated via opening and closing of these slots during seismically induced rotations, while the top concrete hinge is heavily reinforced to prevent material inelastic elongation. Past research on slotted beams has shown that the bond demand on the bottom longitudinal reinforcement is increased compared with equivalent monolithic systems. Satisfying this increased bond demand through conventional means may yield impractical and economically less viable column dimensions. The same research also indicated that the joint shear mechanism was different to that observed within monolithic joints and that additional horizontal reinforcement was required as a result. Through a combination of theoretical investigation, forensic analysis, and database study, this research addresses the above issues and develops design guidelines. The use of supplementary vertical joint stirrups was investigated as a means of improving bond performance without the need for non-standard reinforcing steel or other hardware. These design guidelines were then validated experimentally with the testing of two 80% scale beam-column sub-assemblies. The revised provisions for bond within the bottom longitudinal reinforcement were found to be adequate while the top longitudinal reinforcement remained nominally elastic throughout both tests. An alternate mechanism was found to govern joint shear behaviour, removing the need for additional horizontal joint reinforcement. Current NZS3101:2006 joint shear reinforcement provisions were found to be more than adequate given the typically larger column depths required rendering the strut mechanism more effective. The test results were then used to further refine design recommendations for practicing engineers. Finally, conclusions and future research requirements were outlined.
Earthquake Engineering is facing an extraordinarily challenging era, the ultimate target being set at increasingly higher levels by the demanding expectations of our modern society. The renewed challenge is to be able to provide low-cost, thus more widely affordable, high-seismic-performance structures capable of sustaining a design level earthquake with limited or negligible damage, minimum disruption of business (downtime) or, in more general terms, controllable socio-economical losses. The Canterbury earthquakes sequence in 2010-2011 has represented a tough reality check, confirming the current mismatch between societal expectations over the reality of seismic performance of modern buildings. In general, albeit with some unfortunate exceptions, modern multi-storey buildings performed as expected from a technical point of view, in particular when considering the intensity of the shaking (higher than new code design) they were subjected to. As per capacity design principles, plastic hinges formed in discrete regions, allowing the buildings to sway and stand and people to evacuate. Nevertheless, in many cases, these buildings were deemed too expensive to be repaired and were consequently demolished. Targeting life-safety is arguably not enough for our modern society, at least when dealing with new building construction. A paradigm shift towards damage-control design philosophy and technologies is urgently required. This paper and the associated presentation will discuss motivations, issues and, more importantly, cost-effective engineering solutions to design buildings capable of sustaining low-level of damage and thus limited business interruption after a design level earthquake. Focus will be given to the extensive research and developments in jointed ductile connections based upon controlled rocking & dissipating mechanisms for either reinforced concrete and, more recently, laminated timber structures. An overview of recent on-site applications of such systems, featuring some of the latest technical solutions developed in the laboratory and including proposals for the rebuild of Christchurch, will be provided as successful examples of practical implementation of performance-based seismic design theory and technology.
The Building Act 2004 now requires Territorial Authorities (TAs) to have in place a policy setting out how they intend making existing buildings that would be unable to withstand a moderate earthquake safe for their occupiers. Many of the resultant policies developed by TAs have put in place mandatory upgrade requirements that will force owners to expend large amounts of capital on seismic upgrading of their buildings. The challenge for the property owners and TAs alike is to make such development work economic or the result will be wide scale demolition of old buildings. This has serious implications for both heritage conservation and inner city revitalisation plans that are based on existing heritage buildings. This paper sets out the issues and challenges for the seismic upgrading of buildings in New Zealand and puts forward some potential solutions
The Canterbury earthquakes have generated economic demand and supply volatility, highlighting geographical and structural interdependencies. Post-earthquake reconstruction and new developments have seen skills training, relocation, recruitment and importation of skills becoming crucial for construction companies to meet demand and compete effectively. This report presents 15 case studies from a range of organisations involved in the Canterbury rebuild, exploring the business dynamics and outcomes of their resourcing initiatives. A key finding of this research is that, for many construction organisations, resourcing initiatives have become part of their organisational longer-term development strategies, rather than simply a response to ‘supply and demand’ pressures. Organisations are not relying on any single resourcing solution to drive their growth but use a combination of initiatives to create lasting business benefits, such as cost savings, improved brand and reputation, a stable and productive workforce, enhanced efficiency and staff morale, as well as improved skill levels.
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.
A natural disaster will inevitably strike New Zealand in the coming years, damaging educational facilities. Delays in building quality replacement facilities will lead to short-term disruption of education, risking long-term inequalities for the affected students. The Christchurch earthquake demonstrated the issues arising from a lack of school planning and support. This research proposes a system that can effectively provide rapid, prefabricated, primary schools in post-disaster environments. The aim is to continue education for children in the short term, while using construction that is suitable until the total replacement of the given school is completed. The expandable prefabricated architecture meets the strength, time, and transport requirements to deliver a robust, rapid relief temporary construction. It is also adaptable to any area within New Zealand. This design solution supports personal well-being and mitigates the risk of educational gaps, PTSD linked with anxiety and depression, and many other mental health disorders that can impact students and teachers after a natural disaster.
‘Housing affordability’ has been a term used to refer to a problem that arises when the costs of housing are seen as being unreasonably high in relation to incomes. In the United Kingdom and Australia the local town planning systems have been used to address housing affordability issues. This response in countries that share New Zealand’s town and country planning history raised the question for this research of the local government response to housing affordability issues in the city of Christchurch, New Zealand. This research was undertaken during the fifth year after the 2010/2011 Canterbury earthquake series. Research conducted by the Centre for Housing Research Aotearoa New Zealand and the New Zealand Productivity Commission present quite different pictures of the housing affordability problem, suggest different solutions and indicate different roles for levels of government, the community housing sector and the housing market. The research undertaken for this dissertation aimed to address the question of the role of the state, through the lense of a local response to housing affordability issues, in the context of a central government response focused on land supply and reforming the Resource Management Act 1991.
Non-structural elements (NSEs) have frequently proven to contribute to significant losses sustained from earthquakes in the form of damage, downtime, injury and death. In New Zealand (NZ), the 2010 and 2011 Canterbury Earthquake Sequence (CES), the 2013 Seddon and Cook Strait earthquake sequence and the 2016 Kaikoura earthquake were major milestones in this regard as significant damage to building NSEs both highlighted and further reinforced the importance of NSE seismic performance to the resilience of urban centres. Extensive damage in suspended ceilings, partition walls, façades and building services following the CES was reported to be partly due to erroneous seismic design or installation or caused by intervening elements. Moreover, the low-damage solutions developed for structural systems sometimes allow for relatively large inter-story drifts -compared to conventional designs- which may not have been considered in the seismic design of NSEs. Having observed these shortcomings, this study on suspended ceilings was carried out with five main goals: i) Understanding the seismic performance of the system commonly used in NZ; ii) Understanding the transfer of seismic design actions through different suspended ceiling components, iii) Investigating potential low-damage solutions; iii) Evaluating the compatibility of the current ceiling system with other low-damage NSEs; and iv) Investigating the application of numerical analysis to simulate the response of ceiling systems. The first phase of the study followed a joint research work between the University of Canterbury (UC) in NZ, and the Politecnico Di Milano, in Italy. The experimental ceiling component fragility curves obtained in this existing study were employed to produce analytical fragility curves for a perimeter-fixed ceiling of a given size and weight, with grid acceleration as the intensity measure. The validity of the method was proven through comparisons between this proposed analytical approach with the recommended procedures in proprietary products design guidelines, as well as experimental fragility curves from other studies. For application to engineering design practice, and using fragility curves for a range of ceiling lengths and weights, design curves were produced for estimating the allowable grid lengths for a given demand level. In the second phase of this study, three specimens of perimeter-fixed ceilings were tested on a shake table under both sinusoidal and random floor motion input. The experiments considered the relationship between the floor acceleration, acceleration of the ceiling grid, the axial force induced in the grid members, and the effect of boundary conditions on the transfer of these axial forces. A direct correlation was observed between the axial force (recorded via load cells) and the horizontal acceleration measured on the ceiling grid. Moreover, the amplification of floor acceleration, as transferred through ceiling components, was examined and found (in several tests) to be greater than the recommended factor for the design of ceilings provided in the NZ earthquake loadings standard NZS1170.5. However, this amplification was found to be influenced by the pounding interactions between the ceiling grid members and the tiles, and this amplification diminished considerably when the high frequency content was filtered out from the output time histories. The experiments ended with damage in the ceiling grid connection at an axial force similar to the capacity of these joints previously measured through static tests in phase one. The observation of common forms of damage in ceilings in earthquakes triggered the monotonic experiments carried out in the third phase of this research with the objective of investigating a simple and easily applicable mitigation strategy for existing or new suspended ceilings. The tests focused on the possibility of using proprietary cross-shaped clip elements ordinarily used to provide seismic gap as a strengthening solution for the weak components of a ceiling. The results showed that the solution was effective under both tension and compression loads through increasing load bearing capacity and ductility in grid connections. The feasibility of a novel type of suspended ceiling called fully-floating ceiling system was investigated through shaking table tests in the next phase of this study with the main goal of isolating the ceiling from the surrounding structure; thereby arresting the transfer of associated seismic forces from the structure to the ceiling. The fully-floating ceiling specimen was freely hung from the floor above lacking any lateral bracing and connections with the perimeter. Throughout different tests, a satisfactory agreement between the fully-floating ceiling response and simple pendulum theory was demonstrated. The addition of isolation material in perimeter gaps was found effective in inducing extra damping and protecting the ceiling from pounding impact; resulting in much reduced ceiling displacements and accelerations. The only form of damage observed throughout the random floor motion tests and the sinusoidal tests was a panel dislodgement observed in a test due to successive poundings between the ceiling specimen and the surrounding beams at resonant frequencies. Partition walls as the first effective NSE in direct interaction with ceilings were the topic of the final experimental phase. Low-damage drywall partitions proposed in a previous study in the UC were tested with two common forms of suspended ceiling: braced and perimeter-fixed. The experiments investigated the in-plane and out-of-plane performance of the low-damage drywall partitions, as well as displacement compatibility between these walls and the suspended ceilings. In the braced ceiling experiment, where no connection was made between ceiling grids and surrounding walls no damage in the grid system or partitions was observed. However, at high drift values panel dislodgement was observed on corners of the ceiling where the free ends of grids were not restrained against spreading. This could be prevented by framing the grid ends using a perimeter angle that is riveted only to the grid members while keeping sufficient clearance from the perimeter walls. In the next set of tests with the perimeter-fixed ceiling, no damage was observed in the ceiling system or the drywalls. Based on the results of the experiments it was concluded that the tested ceiling had enough flexibility to accommodate the relative displacement between two perpendicular walls up to the inter-storey drifts achieved. The experiments on perimeter-fixed ceilings were followed by numerical simulations of the performance of these ceilings in a finite element model developed in the structural analysis software, SAP2000. This model was relatively simple and easy to develop and was able to replicate the experimental results to a reasonable degree. Filtering was applied to the experimental output to exclude the effect of high frequency noise and tile-grid impact. The developed model generally simulated the acceleration responses well but underestimated the peak ceiling grid accelerations. This was possibly because the peak values in time histories were affected by impact occurring at very short periods. The model overestimated the axial forces in ceiling grids which was assumed to be caused by the initial assumptions made about the tributary area or constant acceleration associated with each grid line in the direction of excitation. Otherwise, the overall success of the numerical modelling in replicating the experimental results implies that numerical modelling using conventional structural analysis software could be used in engineering practice to analyse alternative ceiling geometries proposed for application to varying structural systems. This however, needs to be confirmed through similar analyses on other ceiling examples from existing instrumented buildings during real earthquakes. As the concluding part of this research the final phase addressed the issues raised following the review of existing ceiling standards and guidelines. The applicability of the research findings to current practice and their implications were discussed. Finally, an example was provided for the design of a suspended ceiling utilising the new knowledge acquired in this research.
<b>Construction and Demolition (C&D) waste contributes to over 50% of New Zealand’s overall waste. Materials such as timber, plasterboard, and concrete make up 81% of the C&D waste that goes into landfills each year. Alongside this, more than 235 heritage-listed buildings have been demolished in Christchurch since the 2011 earthquakes. This research portfolio aims to find a solution to decrease C&D waste produced by demolishing heritage buildings.</b>
With the recent announcement of The Cathedral of the Blessed Sacrament’s demolition, this will be another building added to the list of lost heritage in Christchurch. This research portfolio aims to bridge the relationship between heritage and waste through the recycling and reuse of the demolished materials, exploring the idea that history and heritage are preserved through building material reuse.
This research portfolio mainly focuses on reducing construction and demolition waste in New Zealand, using the design of a new Catholic Cathedral as a vessel. This thesis will challenge how the construction and design industry deals with the demolition of heritage buildings and their contribution to New Zealand’s waste. It aims to explore the idea of building material reuse not only to reduce waste but also to retain the history and heritage of the demolished building within the materials.
There are many swaths of land that are deemed unsuitable to build on and occupy. These places, however, are rarely within an established city. The Canterbury earthquakes of 2010 and 2011 left areas in central Christchurch with such significant land damage that it is unlikely to be re-inhabited for a considerable period of time. These areas are commonly known as the ‘Red Zone’.This thesis explores redevelop in on volatile land through innovative solutions found and adapted from the traditional Indonesian construction techniques. Currently, Indonesia’s vernacular architecture sits on the verge of extinction after a cultural shift towards the masonry bungalow forced a rapid decline in their occupation and construction. The 2004 Indian Ocean earthquake and tsunami illustrated the bungalows’ poor performance in the face of catastrophic seismic activity, being outperformed by the traditional structures. This has been particularly evident in the Rumah Aceh construction of the Aceh province in Northern Sumatra. Within a New Zealand context an adaptation and modernisation of the Rumah Aceh construction will generate an architectural response not currently accepted under the scope of NZS 3604:2011; the standards most recent revision following the Canterbury earthquake of 2010 concerning timber-based seismic performance. This architectural exploration will further address light timber structures, their components, sustainability and seismic resilience. Improving new builds’ durability as New Zealand moves away from the previously promoted bungalow model that extends beyond residential and into all aspects of New Zealand built environment.
Territorial authorities in New Zealand are responding to regulatory and market forces in the wake of the 2011 Christchurch earthquake to assess and retrofit buildings determined to be particularly vulnerable to earthquakes. Pending legislation may shorten the permissible timeframes on such seismic improvement programmes, but Auckland Council’s Property Department is already engaging in a proactive effort to assess its portfolio of approximately 3500 buildings, prioritise these assets for retrofit, and forecast construction costs for improvements. Within the programme structure, the following varied and often competing factors must be accommodated: * The council’s legal, fiscal, and ethical obligations to the people of Auckland per building regulations, health and safety protocols, and economic growth and urban development planning strategies; * The council’s functional priorities for service delivery; * Varied and numerous stakeholders across the largest territorial region in New Zealand in both population and landmass; * Heritage preservation and community and cultural values; and * Auckland’s prominent economic role in New Zealand’s economy which requires Auckland’s continued economic production post-disaster. Identifying those buildings most at risk to an earthquake in such a large and varied portfolio has warranted a rapid field assessment programme supplemented by strategically chosen detailed assessments. Furthermore, Auckland Council will benefit greatly in time and resources by choosing retrofit solutions, techniques, and technologies applicable to a large number of buildings with similar configurations and materials. From a research perspective, the number and variety of buildings within the council’s property portfolio will provide valuable data for risk modellers on building typologies in Auckland, which are expected to be fairly representative of the New Zealand building stock as a whole
Paper 197 An as-built reinforced concrete (RC) frame building designed and constructed according to pre-1970s code design construction practice has been recently tested on the shake table at the University of Canterbury. The specimen, 1/2.5 scaled version of the original prototype, consists of two 3-storey 2-bay asymmetric frames in parallel, one interior and one exterior, jointed together by transverse beams and floor slabs. Following the benchmark test, a retrofit intervention has been proposed to rehabilitate the tested specimen. In this paper, detailed information on the assessment and design of the seismic retrofit procedure using GFRP (glass fibre reinforced polymer) materials is given for the whole frame. Hierarchy of strength and sequence of events (damage mechanisms) in the panel zone region are evaluated using a moment-axial load (M-N) interaction performance domain, according to a performance-based retrofit philosophy. Specific limit states or design objectives are targeted with attention given to both strength and deformation limits. In addition, an innovative retrofit solution using FRP anchor dowels for the corner beam-column joints with slabs is proposed. Finally, in order to provide a practical tool for engineering practice, the retrofit procedure is provided in a step-by step flowchart fashion.
Mr Wayne Tobeck, Director of Southrim Group (SRG), sponsored this 2013 MEM Project titled; A Technical and Economic Feasibility Study for the Integration of GSHP Technology in the Christchurch Rebuild. Following the recent Christchurch earthquakes, a significant amount of land has become too unstable to support traditional building foundations. This creates an opportunity to implement new and unique foundation designs previously unconsidered due to high costs compared to traditional methods. One such design proposes that an Injection Micro-Piling technique could be used. This can also be coupled with HVAC technology to create a Ground Source Heat Pump (GSHP) arrangement in both new buildings and as retrofits for building requiring foundation repair. The purpose of this study was to complete a feasibility study on the merits of SRG pursuing this proposed product. A significant market for such a product was found to exist, while the product was also found to be technically and legally feasible. However, the proposed product was found to not be economically feasible with respect to Air Source Heat Pumps due to the significantly higher capital and installation costs required. Further analysis suggests GSHPs may become more economically attractive in operating temperatures lower than -9oC, though the existence of markets with this climate in NZ has not been studied. It is therefore suggested that SRG do not proceed with plans to develop a GSHP coupled foundation solution for the Christchurch rebuild.
Timber-based hybrid structures provide a prospective solution for utilizing environmentally friendly timber material in the construction of mid-rise or high-rise structures. This study mainly focuses on structural damage evaluation for a type of timber-steel hybrid structures, which incorporate prefabricated light wood frame shear walls into steel moment-resisting frames (SMRFs). The structural damage of such a hybrid structure was evaluated through shake table tests on a four-story large-scale timber-steel hybrid structure. Four ground motion records (i.e., Wenchuan earthquake, Canterbury earthquake, El-Centro earthquake, and Kobe earthquake) were chosen for the tests, with the consideration of three different probability levels (i.e., minor, moderate and major earthquakes) for each record. During the shake table tests, the hybrid structure performed quite well with visual damage only to wood shear walls. No visual damage in SMRF and the frame-to-wall connections was observed. The correlation of visual damage to seismic intensity, modal-based damage index and inter-story drift was discussed. The reported work provided a basis of knowledge for performance-based seismic design (PBSD) for such timber-based hybrid structures.
Today there is interest in building resilient communities. Identifying and managing the risks of natural hazards with communities who face compounding hazards is challenging. Alpine ski areas provide a unique context to study this challenging and complex process. The traditional approach taken to manage natural hazards is discipline-centric and focuses on common (e.g. high probability low consequence) natural hazards such as avalanches. While this thesis acknowledges that the common approach is rational, it argues that we can extend our communities of practice to include rare (e.g. low probability / high consequence) natural hazards such as earthquakes. The dynamically complex nature of these ‘rare’ hazards limits our understanding about them, but by seeking and using the lived experiences of people in mountain communities some knowledge can be gained to help improve our understanding of how to adapt. This study focuses on such an approach in the context of alpine ski areas prone to earthquakes as a first step toward identifying key policy opportunities for hazard mitigation in general. The contributions can be broken down into methodological, contextual, and theoretical pursuits, as well as opportunities for improving future research. A development mixed method triangulated approach was justified because the research problem (i.e. earthquakes in ski areas) has had little consideration. The context provided the opportunity to test the integration of methods while dealing with the challenges of research in a novel context. Advancement to fuzzy cognitive mapping was achieved through the use of unsupervised neural networks (Self-organizing Maps or Kohonen Maps). The framework applied in the multi-site case study required a synthesis of current approaches, advances to methods and a functional use of cultural theory. Different approaches to participatory policy development were reviewed to develop a research protocol that was accessible. Cultural theory was selected as a foundation for the thesis because of its’ preference for plural rationalities from five ways of organizing. Moreover, the study undertook a shift away from the dichotomy of ‘methodological individualism’ and ‘methodological collectivism’ and instead chose the dividual (i.e. social solidarities that consist of culural biases, behavioral strategies and social relations) as a consistent unit of analysis despite three different methodologies including: field studies, qualitative interviews, and fuzzy cognitive maps. In this sense, the thesis sought to move away from ‘elegant solutions’ from singular solidarities or methods toward a research philosophy that sustains requisite variety and clumsy solutions. Overall the approach was a trandisciplinary framework that is a step toward sustainable hazards mitigation. The results indicate that the selections of risks and adaptation strategies associated with the in-situ hazards are driven by roles that managers, workers, and riders play in the context. Additionally, fuzzy cognitive maps were used as an extension of qualitative interviews and demonstrated the potential for power struggles that may arise between participant groups when considering strategies for preparation, response and recovery. Moreover, the results stress that prolonged engagement with stakeholders is necessary to improve the policy development process. Some comments are made on the compatibility condition of congruence between cultural biases, behavioural strategies, and social relations. As well, inclusion of the hermit/autonomous solidarities is stressed as a necessary component of future applications of cultural theory. The transdisciplinary mixed-method framework is an approach that can be transferred to many other vital areas of research where integration is desirable.
The skills agenda has grown in prominence within the construction industry. Indeed, skill shortages have been recognised as a perennial problem the construction industry faces, especially after a major disaster. In the aftermath of the Christchurch earthquakes, small and medium construction companies were at the forefront of rebuilding efforts. While the survival of these companies was seen to be paramount, and extreme events were seen to be a threat to survival, there is a dearth of research centring on their resourcing capacity following a disaster. This research aims to develop workforce resourcing best practice guidelines for subcontractors in response to large disaster reconstruction demands. By using case study methods, this research identified the challenges faced by subcontracting businesses in resourcing Christchurch recovery projects; identified the workforce resourcing strategies adopted by subcontracting businesses in response to reconstruction demand; and developed a best practice guideline for subcontracting businesses in managing the workforce at the organisational and/or project level. This research offers a twofold contribution. First, it provides an overview of workforce resourcing practices in subcontracting businesses. This understanding has enabled the development of a more practical workforce resourcing guideline for subcontractors. Second, it promotes evidence-informed decision-making in subcontractors’ workforce resourcing. Dynamics in workforce resourcing and their multifaceted interactions were explicitly depicted in this research. More importantly, this research provides a framework to guide policy development in producing a sustainable solution to skill shortages and establishing longterm national skill development initiatives. Taken together, this research derives a research agenda that maps under-explored areas relevant for further elaboration and future research. Prospective researchers can use the research results in identifying gaps and priority areas in relation to workforce resourcing
Paper 201 In order to provide information related to seismic vulnerability of non-ductile reinforced concrete (RC) frame buildings, and as a complementary investigation on innovative feasible retrofit solutions developed in the past six years at the University of Canterbury on pre-19170 reinforced concrete buildings, a frame building representative of older construction practice was tested on the shake table. The specimen, 1/2.5 scale, consists of two 3-storey 2-bay asymmetric frames in parallel, one interior and one exterior, jointed together by transverse beams and floor slabs. The as-built (benchmark) specimen was first tested under increasing ground motion amplitudes using records from Loma Prieta Earthquake (California, 1989) and suffered significant damage at the upper floor, most of it due to lap splices failure. As a consequence, in a second stage, the specimen was repaired and modified by removing the concrete in the lap splice region, welding the column longitudinal bars, replacing the removed concrete with structural mortar, and injecting cracks with epoxy resin. The modified as-built specimen was then tested using data recorded during Darfield (New Zealand, 2010) and Maule (Chile, 2010) Earthquakes, with whom the specimen showed remarkably different responses attributed to the main variation in frequency content and duration. In this contribution, the seismic performance of the three series of experiments are presented and compared.
