We present preliminary observations on three waters impacts from the Mw7.8 14th November 2016 Kaikōura Earthquake on wider metropolitan Wellington, urban and rural Marlborough, and in Kaikōura township. Three waters systems in these areas experienced widespread and significant transient ground deformation in response to seismic shaking, with localised permanent ground deformation via liquefaction and lateral spreading. In Wellington, potable water quality was impacted temporarily by increased turbidity, and significant water losses occurred due to damaged pipes at the port. The Seaview and Porirua wastewater treatment plants sustained damage to clarifier tanks from water seiching, and increased water infiltration to the wastewater system occurred. Most failure modes in urban Marlborough were similar to the 2010-2011 Canterbury Earthquake Sequence; however some rural water tanks experienced rotational and translational movements, highlighting importance of flexible pipe connections. In Kaikōura, damage to reservoirs and pipes led to loss of water supply and compromised firefighting capability. Wastewater damage led to environmental contamination, and necessitated restrictions on greywater entry into the system to minimise flows. Damage to these systems necessitated the importation of tankered and bottled water, boil water notices and chlorination of the system, and importation of portaloos and chemical toilets. Stormwater infrastructure such as road drainage channels was also damaged, which could compromise condition of underlying road materials. Good operational asset management practices (current and accurate information, renewals, appreciation of criticality, good system knowledge and practical contingency plans) helped improve system resilience, and having robust emergency management centres and accurate Geographic Information System data allowed effective response coordination. Minimal damage to the wider built environment facilitated system inspections. Note Future research will include detailed geospatial assessments of seismic demand on these systems and attendant modes of failure, levels of service restoration, and collaborative development of resilience measures.
Recent advances in timber design at the University of Canterbury have led to new structural systems that are appropriate for a wide range of building types, including multi-storey commercial office structures. These buildings are competitive with more traditional construction materials in terms of cost, sustainability and structural performance. This paper provides seismic design recommendations and analytical modelling approaches, appropriate for the seismic design of post-tensioned coupled timber wall systems. The models are based on existing seismic design theory for precast post-tensioned concrete, modified to more accurately account for elastic deformation of the timber wall systems and the influence of the floor system. Experimental test data from a two storey post-tensioned timber building, designed, constructed and tested at the University of Canterbury is used to validate the analytical models.
A video of a presentation by Assistant Professor Paolo Franchin of Sapienza University of Rome on "Modelling seismic vulnerability and resilience of interconnected infrastuctural systems". The presentation was delivered at the learning forum on Interdependencies of Lifeline Systems as part of the University of Canterbury's Lifeline Week.
The University of Canterbury has initialized a research program focusing on the seismic sustainability of structures. As part of this program, the relative seismic sustainability of various structures will be assessed to identify those with the highest sustainability for the Christchurch rebuild and general use in New Zealand. This preliminary case study assesses one reinforced concrete (RC) frame structure and one RC wall structure. The scenario loss is evaluated for two earthquake records considering direct losses only in order to explain and illustrate the methodology.
Major earthquakes, such as the Canterbury and Kaikoura events recorded in New Zealand in 2010 and 2016 respectively, highlighted that floor systems can be heavily damaged. At a reduced or full scale, quasi-static experimental tests on structural sub-assemblies can help to establish the seismic performance of structural systems. However, the experimental performance obtained with such tests is likely to be dependent on the drift protocol adopted. This paper provides an overview of the drift protocols which have been assumed in previous relevant experimental activities, with emphasis on those adopted for testing floor systems. The paper also describes the procedure used to define the loading protocol applied in the testing of a large precast concrete floor diaphragm as part of the Recast floor project at the University of Canterbury. Finally, major limits of current loading protocols, and areas of future research, are identified.
There is an increasing recognition that the seismic performance of buildings will be affected by the behaviour of both structural and non-structural elements. In light of this, work has been progressing at the University of Canterbury to develop guidelines for the seismic assessment of commercial glazing systems. This paper reviews the seismic assessment guidelines prescribed in Section C10 of the MBIE building assessment guidelines. Subsequently, the C10 approach is used to assess the drift capacity of a number of glazing units recently tested at the University of Canterbury. Comparing the predicted and observed drift capacities, it would appear that the C10 guidelines may lead to nonconservative estimates of drift capacity. Furthermore, the experimental results indicate that watertightness may be lost at very low drift demands, suggesting that guidance for the assessment of serviceability performance would also be beneficial. As such, it is proposed that improved guidance be provided to assist engineers in considering the possible impact that glazing could have on the structural response of a building in a large earthquake.
A video of a presentation by Associate Professor Leonardo Duenas-Osorio of Rice University in Texas on "On-going and planned activities of the TCLEE Lifeline Systems Interdependence Committee". The presentation was delivered at the learning forum on Interdependencies of Lifeline Systems as part of the University of Canterbury's Lifeline Week.
Earthquakes cause significant damage to buildings due to strong vibration of the ground. Levitating houses using magnets and electromagnets would provide a complete isolation of ground motion for protecting buildings from seismic damage. Two types of initial configuration for the electromagnet system were proposed with the same air gap (10mm) between the electromagnet and reluctance plate. Both active and passive controller are modelled to investigate the feasibility of using a vibration control system for stabilizing the magnetic system within the designed air gap (10mm) in the vertical direction. A nonlinear model for the magnetic system is derived to implement numerical simulation of structural response under the earthquake record in Christchurch Botanic Gardens on 21 February 2011. The performance of the uncontrolled and the controlled systems are compared and the optimal combination of control gains are determined for the PID active controller. Simulation results show both active PID controller with constant and nonlinear attracting force are able to provide an effective displacement control within the required air gap (+/-5mm). The maximum control force demand for the PID controller in the presence of nonlinear attracting force is 4.1kN, while the attracting force in equilibrium position is 10kN provided by the electromagnet. These results show the feasibility of levitating a house using the current electromagnet and PID controller. Finally, initial results of passive control using two permanent magnets or dampers show the structural responses can be effectively reduced and centralized to +/-1mm using a nonlinear centring barrier function.
In recent Canterbury earthquakes, structures have performed well in terms of life safety but the estimated total cost of the rebuild was as high as $40 billion. The major contributors to this cost are repair/demolition/rebuild cost, the resulting downtime and business interruption. For this reason, the authors are exploring alternate building systems that can minimize the downtime and business interruption due to building damage in an earthquake; thereby greatly reducing the financial implications of seismic events. In this paper, a sustainable and demountable precast reinforced concrete (RC) frame system in which the precast members are connected via steel tubes/plates or steel angles/plates and high strength friction grip (HSFG) bolts is introduced. In the proposed system, damaged structural elements in seismic frames can be easily replaced with new ones; thereby making it an easily and quickly repairable and a low-loss system. The column to foundation connection in the proposed system can be designed either as fixed or pinned depending on the requirement of strength and stiffness. In a fixed base frame system, ground storey columns will also be damaged along with beams in seismic events, which are to be replaced after seismic events; whereas in a pin base frame only beams (which are easy to replace) will be damaged. Low to medium rise (3-6 storey) precast RC frame buildings with fixed and pin bases are analyzed in this paper; and their lateral capacity, lateral stiffness and natural period are scrutinized to better understand the pros and cons of the demountable precast frame system with fixed and pin base connections.
In recent years, rocking isolation has become an effective approach to improve seismic performance of steel and reinforced concrete structures. These systems can mitigate structural damage through rigid body displacement and thus relatively low requirements for structural ductility, which can significantly improve seismic resilience of structures and reduce repairing costs after strong earthquakes. A number of base rocking structural systems with only a single rocking interface have been proposed. However, these systems can have significant high mode effect for high rise structures due to the single rocking interface. This RObust BUilding SysTem (ROBUST) project is a collaborative China-New Zealand project sponsored by the International Joint Research Laboratory of Earthquake Engineering (ILEE), Tongji University, and a number of agencies and universities within New Zealand including the BRANZ, Comflor, Earthquake Commission, HERA, QuakeCoRE, QuakeCentre, University of Auckland, and the University of Canterbury. A number of structural configurations will be tested [1, 2], and non-structural elements including ceilings, infilling walls, glazed curtain walls, precast concrete panels, piping system will also be tested in this project [3]. Within this study, a multiple rocking column steel structural system was proposed and investigated mainly by Tongji team with assistance of NZ members. The concept of rocking column system initiates from the structure of Chinese ancient wooden pagoda. In some of Chinese wooden pagodas, there are continuous core columns hanged only at the top of each pagoda, which is not connected to each stories. This core column can effectively avoid collapse of the whole structure under large storey drifts. Likewise, there are also central continuous columns in the newly proposed steel rocking column system, which can avoid weak story failure mechanism and make story drifts more uniform. In the proposed rocking column system, the structure can switch between an elastic rigidly connected moment resisting frame and a controlled rocking column system when subjected to strong ground motion excitations. The main seismic energy can be dissipated by asymmetric friction beam–column connections, thereby effectively reducing residual displacement of the structure under seismic loading without causing excessive damage to structural members. Re–centering of the structure is provided not only by gravity load carried by rocking columns, but also by mould coil springs. To investigate dynamic properties of the proposed system under different levels of ground excitations, a full-scale threestory steel rocking column structural system with central continuous columns is to be tested using the International joint research Laboratory of Earthquake Engineering (ILEE) facilities, Shanghai, China and an analytical model is established. A finite element model is also developed using ABAQUS to simulate the structural dynamic responses. The rocking column system proposed in this paper is shown to produce resilient design with quick repair or replacement.
A copy of the award application for the New Zealand Engineering Excellence Awards 2013.
Glazing systems are non-structural elements in a building that, more often than not, appear to be given little consideration in seismic design. Recent experimental work into glazing systems at the University of Canterbury, however, has shown that glazing systems can be very susceptible to serviceability damage, defined as loss of water-tightness. The focus of this paper is to highlight the difference in vulnerability of standard and seismic glazing systems and consider the implications of this for future repair costs and losses. The paper first describes the damage states chosen for glazing units according to the repair strategies required and expected repair costs. This includes three damage states: DS1: Water Leakage, DS2: Gasket Failure and DS3: Frame/Glass Failure. Implementing modern performance-based earthquake engineering, the paper proceeds to highlight a case study comparing costs and expected losses of a standard glazing unit and a seismic glazing unit installed on a case study building. It is shown that the use of seismic glazing units is generally beneficial over time, due to the early onset of serviceability damage in standard glazing units. Finally, the paper provides suggestions for designers aimed at reducing costs related to earthquake induced repairs of glazing.
A one story, two bays, approximately half scaled, perimeter moment frame containing precastprestressed floor units was built and tested at the University of Canterbury to investigate the effect of precastprestressed floor units on the seismic performance of reinforced concrete moment resisting frame. This paper gives an overview of the experimental set up and summarizes the results obtained from the test. The results show that elongation in the beam plastic hinges is partially restrained by the prestressed floor, which increases the strength of the beams much more than that being specified in the codes around the world.
A video of a presentation by Indranil Kongar of University College London on "Lifeline systems interdependencies: the insurance perspective". The presentation was delivered at the learning forum on Interdependencies of Lifeline Systems as part of the University of Canterbury's Lifeline Week.
A video of a presentation by Associate Professor Leonardo Duenas-Osorio of Rice University in Texas on "Learning and planning collaboration on 'Inderdependencies of Lifeline Systems' workshop". The presentation was delivered at the Learning from Lifeline Week and Planning Collaborations forum as part of the University of Canterbury's Lifeline Week.
A video of a presentation by Professor Rachel A. Davidson of the University of Delaware on "System Resilience: Probabilistic scenario-based approach for prioritising mitigation-strategies". The presentation was delivered at the Learning from Lifeline Week and Planning Collaborations forum as part of the University of Canterbury's Lifeline Week.
Recent severe earthquakes, such as the 2010-2011 Christchurch earthquake series, have put emphasis on building resilience all over the world. To achieve such resilience, procedures for low damage seismic design have been developed to satisfy both life safety requirements and the need to minimize undesirable economic effects of required building repair or structural member replacement following a major earthquake. Seismic resisting systems following this concept are expected to withstand severe earthquakes without requiring major post-earthquake repairs, using isolating mechanisms or sacrificial systems that either do not need repair or are readily repairable or replaceable. These include the sliding hinge joint with asymmetric friction connections (SHJAFCs) in beam-to-column connections of the moment resisting steel frames (MRSFs) and symmetric friction connections (SFCs) in braces of the braced frames. A 9 m tall, configurable three-storey steel framed composite floor building incorporating frictionbased connections is to be tested using two linked bi-directional shake tables at the International joint research Laboratory of Earthquake Engineering (ILEE) facilities, Shanghai, China. The structural systems are configurable, allowing different moment and braced frame structural systems tested in two horizontal directions. The structure is designed and detailed to undergo, at worst, minor damage under a planned series of severe earthquakes.
A multi-disciplinary geo-structural-environmental engineering project funded by the Ministry of Business Innovation and Employment (MBIE) is being carried out at the University of Canterbury. The project aims at developing an eco-friendly seismic isolation foundation system which will improve the seismic performance of medium-density low-rise buildings. Such system is characterized by two main elements: 1) granulated scrap rubber mixed with gravelly soils to be placed beneath the structure, with the goal damping part of the seismic energy before it reaches the superstructure; and 2) a basement raft made of steel-fibre reinforced rubberised concrete (SFRRuC) to enhance the flexibility and toughness of the foundation, looking at better accommodating the displacement demand. In this paper, the main objectives, scope and methodology of the project will be briefly described. A literature review of the engineering properties of steel-fibre reinforced rubberised concrete (RuC) will be presented. Then, preliminary results on concrete mixes with different rubber and steel fibres content will be exhibited.
A preliminary case study assessing the seismic sustainability of two reinforced concrete structures, a frame structure and a wall structure, was conducted to determine which structural system is more seismically sustainable. The two structures were designed to the same standards and were assumed to be located in Christchurch, New Zealand. A component-based probabilistic seismic loss assessment, considering direct losses only, was conducted for two ground motion records, regarded to approximately represent a 1 in 500 year earthquake event and a 1 in 2500 year earthquake event, respectively. It is shown that the wall structure results in lower direct losses than the frame structure in the less severe ground motion scenario. However, in the more severe ground motion scenario, the frame structure results in lower direct losses. Hence, this study demonstrates that which structural system has the lower direct losses depends on the ground motion intensity level.
Over 6.3 million waste tyres are produced annually in New Zealand (Tyrewise, 2021), leading to socioeconomic and environmental concerns. The 2010-11 Canterbury Earthquake Sequence inflicted extensive damage to ~6,000 residential buildings, highlighting the need to improve the seismic resilience of the residential housing sector. A cost-effective and sustainable eco-rubber geotechnical seismic isolation (ERGSI) foundation system for new low-rise buildings was developed by the authors. The ERGSI system integrates a horizontal geotechnical seismic isolation (GSI) layer i.e., a deformable seismic energy dissipative filter made of granulated tyre rubber (GTR) and gravel (G) – and a flexible rubberised concrete raft footing. Geotechnical experimental and numerical investigations demonstrated the effectiveness of the ERGSI system in reducing the seismic demand at the foundation level (i.e., reduced peak ground acceleration) (Hernandez et al., 2019; Tasalloti et al., 2021). However, it is essential to ensure that the ERGSI system has minimal leaching attributes and does not result in long-term negative impacts on the environment.
This paper describes the performance of (or damage to) ceilings in buildings during the 22nd February 2011 Christchurch earthquake and the subsequent aftershocks. In buildings that suffered severe structural damage, ceilings and other non-structural components (rather expectedly) failed, but even in buildings with little damage to their structural systems, ceilings were found to be severely damaged. The extent of ceiling damage, where the ceilings were subject to severe shaking, depended on the type of the ceiling system, the size and weight of the ceilings and the interaction of ceilings with other elements. The varieties and extent of observed ceiling damage are discussed in this paper with the help of photographs taken after the earthquake.
The devastating magnitude M6.3 earthquake, that struck the city of Christchurch at 12:51pm on Tuesday 22 February 2011, caused widespread damage to the lifeline systems. Following the event, the Natural Hazard Research Platform (NHRP) of New Zealand funded a short-term project “Recovery of Lifelines” aiming to: 1) coordinate the provision of information to meet lifeline short-term needs; and to 2) facilitate the accessibility to lifelines of best practice engineering details, along with hazards and vulnerability information already available from the local and international scientific community. This paper aims to briefly summarise the management of the recovery process for the most affected lifelines systems, including the electric system, the road, gas, and the water and wastewater networks. Further than this, the paper intends to discuss successes and issues encountered by the “Recovery of Lifelines” NHRP project in supporting lifelines utilities.
Shaking table testing of a full-scale three storey resilient and reparable complete composite steel framed building system is being conducted. The building incorporates a number of interchangeable seismic resisting systems of New Zealand and Chinese origin. The building has a steel frame and cold formed steel-concrete composite deck. Energy is dissipated by means of friction connections. These connections are arranged in a number of structural configurations. Typical building nonskeletal elements (NSEs) are also included. Testing is performed on the Jiading Campus shaking table at Tongji University, Shanghai, China. This RObust BUilding SysTem (ROBUST) project is a collaborative China-New Zealand project sponsored by the International Joint Research Laboratory of Earthquake Engineering (ILEE), Tongji University, and a number of agencies and universities within New Zealand including BRANZ, Comflor, Earthquake Commission, HERA, QuakeCoRE, QuakeCentre, University of Auckland, and the University of Canterbury. This paper provides a general overview of the project describing a number of issues encountered in the planning of this programme including issues related to international collaboration, the test plan, and technical issues.
In the aftermath of the 22 February 2011 earthquake, the Natural Hazards Research Platform (NHRP) initiated a series of Short Term Recovery Projects (STRP) aimed at facilitating and supporting the recovery of Christchurch from the earthquake impacts. This report presents the outcomes of STRP 6: Impacts of Liquefaction on Pipe Networks, which focused on the impacts of liquefaction on the potable water and wastewater systems of Christchurch. The project was a collaborative effort of NHRP researchers with expertise in liquefaction, CCC personnel managing and designing the systems and a geotechnical practitioner with experience/expertise in Christchurch soils and seismic geotechnics.
Improving community resilience requires a way of thinking about the nature of a community. Two complementary aspects are proposed: the flows connecting the community with its surrounding environment and the resources the community needs for its ongoing life. The body of necessary resources is complex, with many interactions between its elements. A systems approach is required to understand the issues adequately. Community resilience is discussed in general terms together with strategies for improving it. The ideas are then illustrated and amplified by an extended case study addressing means of improving the resilience of a community on the West Coast of New Zealand to natural disasters. The case study is in two phases. The first relies on a mix of on-the-ground observations and constructed scenarios to provide recommendations for enhancing community resilience, while the second complements the first by developing a set of general lessons and issues to be addressed from observations of the Christchurch earthquakes of 2010 and 2011.
Recent severe earthquakes, such as Christchurch earthquake series, worldwide have put emphasis on building resilience. In resilient systems, not only life is protected, but also undesirable economic effects of building repair or replacement are minimized following a severe earthquake. Friction connections are one way of providing structure resilience. These include the sliding hinge joint with asymmetric friction connections (SHJAFCs) in beam-to-column connections of the moment resisting steel frames (MRSFs), and the symmetric friction connections (SFCs) in braces of the braced frames. Experimental and numerical studies on components have been conducted internationally. However, actual building performance depends on the many interactions, occurring within a whole building system, which may be difficult to determine accurately by numerical modelling or testing of structural components alone. Dynamic inelastic testing of a full-scale multi-storey composite floor building with full range of non-structural elements (NSEs) has not yet been performed, so it is unclear if surprises are likely to occur in such a system. A 9 m tall three-storey configurable steel framed composite floor building incorporating friction-based connections is to be tested using two linked bi-directional shake tables at the International joint research Laboratory of Earthquake Engineering (ILEE) facilities, Shanghai, China. Beams and columns are designed to remain elastic during an earthquake event, with all non-linear behaviour occurring through stable sliding frictional behaviour, dissipating energy by SHJAFCs used in MRFs and SFCs in braced frames, with and without Belleville springs. Structural systems are configurable, allowing different moment and braced frame structural systems to be tested in two horizontal directions. In some cases, these systems interact with rocking frame or rocking column system in orthogonal directions subjected to unidirectional and bidirectional horizontal shaking. The structure is designed and detailed to undergo, at worst, minor damage under series of severe earthquakes. NSEs applied include precast-concrete panels, glass curtain walling, internal partitions, suspended ceilings, fire sprinkler piping as well as some other common contents. Some of the key design considerations are presented and discussed herein
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.
Damage to ceiling systems resulted in a substantial financial loss to building owners in the Canterbury earthquakes. In some buildings, collapse of ceilings could easily have resulted in severe injury to occupants. This paper summarizes the types of ceiling damage observed in the Canterbury earthquakes, and draws useful lessons from the observed performance of different types of ceiling systems. Existing ceiling manufacturing and installing practices/regulations in New Zealand are critically scrutinized to identify deficiencies, and measures are suggested to improve the practice so that the damage to ceilings and the resulting loss are minimized in future earthquakes.
An earthquake memories story from Alan Bavis, Facilities and Engineering Manager, 33 St Asaph Street, titled, "Big team effort".
A video of a presentation by Dr Rob Buxton of GNS Science on "Modelling interdependencies of critical infrastructure". The presentation was delivered at the learning forum on Interdependencies of Lifeline Systems as part of the University of Canterbury's Lifeline Week.
