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Images, UC QuakeStudies

Members of the public take photographs of the damaged Christ Church Cathedral. A walkway from Gloucester Street to the Square was opened up for a few days to allow the public a closer look at the cathedral. The tower and the front wall of the building have partially collapsed. Steel bracing has been added to the front wall for support.

Images, UC QuakeStudies

Steel bracing on the front of the Worcester Street face of the Octagon Live Restaurant (formerly Trinity Church), which is being repaired. The scaffolding has been decorated with sculptures of people kayaking, cycling, climbing and bungee jumping. Some of the figures are wearing santa hats. A fence has been constructed at the base of the building.

Images, UC QuakeStudies

Steel bracing on the front of the Worcester Street face of the Octagon Live Restaurant (formerly Trinity Church), which is being repaired. The scaffolding has been decorated with sculptures of people kayaking, cycling, climbing and bungee jumping. Some of the figures are wearing santa hats. A fence has been constructed at the base of the building.

Images, UC QuakeStudies

A photograph of the Christchurch Arts Centre taken from Rolleston Avenue. A spire has been removed from one of the towers and braced on the footpath in front of the building. Wire fencing and road cones have been used to cordon off one side of the road.

Images, UC QuakeStudies

A photograph of the earthquake damage to the Piko Wholefoods Building on the corner of Kilmore and Barbadoes Street. Sections of the top storey of the building have collapsed and the bricks and other rubble have spilled onto the footpath below. Steel fences have been placed around the building as a cordon.

Images, UC QuakeStudies

The Wizard of Christchurch talks to a member of the public outside the damaged cathedral. A walkway from Gloucester Street to the Square was opened up for a few days to allow the public a closer look at the cathedral. The tower and the front wall of the building have partially collapsed. Steel bracing has been added to the front wall for support.

Images, UC QuakeStudies

A photograph of the earthquake damage to the Kenton Chambers Building on Hereford Street. Large cracks have formed in the columns between the building's windows. A section on the bottom storey has collapsed and the bricks have spilled onto the footpath in front. Steel fences have been placed across the street as a cordon.

Images, UC QuakeStudies

A photograph of a piece of plywood sitting on top of a pile of bricks from the Carlton Hotel. USAR codes have been spray-painted on the wood. In the foreground, metal fencing, cordon tape and a road cone have been used to cordon off the building.

Research papers, The University of Auckland Library

Five years after the devastating series of earthquakes in Christchurch, New Zealand, the structural engineering community is now focussing on low damage design by either proactively reducing the possibility of significant damage to primary steel members (i.e. developing seismic resisting systems that will deliver a high damage threshold in severe earthquakes) or by improved detailing of the primary steel members for rapid replacement. This paper presents a development of Eccentrically Braced Frames (EBFs) with replaceable active links. It uses the bolted flange- and web splicing concept to connect the active link to the collector beam or column. Finite element analyses have been performed to investigate the behaviour and reliability of EBFs with this new type replaceable active link. The results show a stable hysteretic behaviour and more significantly easier replacement of the damaged active link in comparison with conventional EBFs.

Images, UC QuakeStudies

A photograph of a building on the corner of Victoria Street and Bealey Avenue. Large sections of the building have collapsed and the bricks have spilled onto the footpath below. Scaffolding has been constructed around the rest of the building, blocking it from view. In the foreground steel fencing and road cones have been placed across Victoria Street as a cordon.

Images, UC QuakeStudies

A photograph of emergency management personnel walking down Manchester Street towards the intersection of High and Lichfield Streets. Many of the buildings on the left side of the road have been damaged by the earthquakes. In the distance rubble from the earthquake-damaged buildings has spilled onto the road. Steel fences have been placed along the footpath to the left.

Images, UC QuakeStudies

A poem written on Gap Filler and Poetica's "Instant Poetry" wall on Colombo Street. The poem reads, "Amidst the shards of glass and twisted steel, beside the fallen brick and scattered concrete, we began to understand that there is beauty in the broken. Strangers do not live here anymore". This poem was picked by the public as the favourite poem written on the wall. It was then painted permanently onto the mural.

Images, UC QuakeStudies

A photograph of the earthquake damage to the Kenton Chambers Building on Hereford Street. Large cracks have formed in the columns between the building's windows. A section of the bottom storey has collapsed and the bricks have spilled onto the footpath in front. Steel fences have been placed on the street as a cordon. In the distance there are many other earthquake-damaged buildings.

Research papers, University of Canterbury Library

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

Images, UC QuakeStudies

A photograph of the north side of the ChristChurch Cathedral in Cathedral Square. The front of the building has been propped up with steel bracing but further earthquakes have caused more damage, leaving a gap between the bracing and the wall. The tower has been partially demolished, but the lower section is still visible. Wire fencing has been placed around the entire building. In the background, a crane is rising high above the square.

Images, UC QuakeStudies

A photograph of the north side of the ChristChurch Cathedral in Cathedral Square. The front of the building has been propped up with steel bracing but further earthquakes have caused more damage, leaving a gap between the bracing and the wall. The tower has been partially demolished, but the lower section is still visible. Wire fencing has been placed around the entire building. In the background, a crane is rising high above the square.

Images, UC QuakeStudies

The ruins of the historic Durham Street Methodist Church in the aftermath of the 22 February 2011 earthquake. The only parts of the building still upright are those supported by steel braces placed there after the 4 September 2010 earthquake to strengthen the building as it awaited repairs. Rubble has spilled out onto the street, knocking over the safety fences that were also erected after September. Silt from liquefaction has covered the road around the church.

Images, UC QuakeStudies

A photograph of the north side of the ChristChurch Cathedral in Cathedral Square. The front of the building has been propped up with steel bracing but further earthquakes have caused more damage, leaving a gap between the bracing and the wall. The tower has been partially demolished, but the lower section is still visible. Wire fencing has been placed around the entire building. In the background, a crane is rising high above the square.

Research papers, University of Canterbury Library

One of the most controversial issues highlighted by the 2010-2011 Christchurch earthquake series and more recently the 2016 Kaikoura earthquake, has been the evident difficulty and lack of knowledge and guidelines for: a) evaluation of the residual capacity damaged buildings to sustain future aftershocks; b) selection and implementation of a series of reliable repairing techniques to bring back the structure to a condition substantially the same as prior to the earthquake; and c) predicting the cost (or cost-effectiveness) of such repair intervention, when compared to fully replacement costs while accounting for potential aftershocks in the near future. As a result of such complexity and uncertainty (i.e., risk), in combination with the possibility (unique in New Zealand when compared to most of the seismic-prone countries) to rely on financial support from the insurance companies, many modern buildings, in a number exceeding typical expectations from past experiences at an international level, have ended up being demolished. This has resulted in additional time and indirect losses prior to the full reconstruction, as well as in an increase in uncertainty on the actual relocation of the investment. This research project provides the main end-users and stakeholders (practitioner engineers, owners, local and government authorities, insurers, and regulatory agencies) with comprehensive evidence-based information to assess the residual capacity of damage reinforced concrete buildings, and to evaluate the feasibility of repairing techniques, in order to support their delicate decision-making process of repair vs. demolition or replacement. Literature review on effectiveness of epoxy injection repairs, as well as experimental tests on full-scale beam-column joints shows that repaired specimens have a reduced initial stiffness compared with the undamaged specimen, with no apparent strength reduction, sometimes exhibiting higher displacement ductility capacities. Although the bond between the steel and concrete is only partially restored, it still allows the repaired specimen to dissipate at least the same amount of hysteretic energy. Experimental tests on buildings subjected to earthquake loading demonstrate that even for severe damage levels, the ability of the epoxy injection to restore the initial stiffness of the structure is significant. Literature review on damage assessment and repair guidelines suggests that there is consensus within the international community that concrete elements with cracks less than 0.2 mm wide only require cosmetic repairs; epoxy injection repairs of cracks less and 2.0 mm wide and concrete patching of spalled cover concrete (i.e., minor to moderate damage) is an appropiate repair strategy; and for severe damaged components (e.g., cracks greater than 2.0 mm wide, crushing of the concrete core, buckling of the longitudinal reinforcement) local replacement of steel and/or concrete in addition to epoxy crack injection is more appropriate. In terms of expected cracking patterns, non-linear finite element investigations on well-designed reinforced concrete beam-to-column joints, have shown that lower number of cracks but with wider openings are expected to occur for larger compressive concrete strength, f’c, and lower reinforcement content, ρs. It was also observed that the tensile concrete strength, ft, strongly affects the expected cracking pattern in the beam-column joints, the latter being more uniformly distributed for lower ft values. Strain rate effects do not seem to play an important role on the cracking pattern. However, small variations in the cracking pattern were observed for low reinforcement content as it approaches to the minimum required as per NZS 3101:2006. Simple equations are proposed in this research project to relate the maximum and residual crack widths with the steel strain at peak displacement, with or without axial load. A literature review on fracture of reinforcing steel due to low-cycle fatigue, including recent research using steel manufactured per New Zealand standards is also presented. Experimental results describing the influence of the cyclic effect on the ultimate strain capacity of the steel are also discussed, and preliminary equations to account for that effect are proposed. A literature review on the current practice to assess the seismic residual capacity of structures is also presented. The various factors affecting the residual fatigue life at a component level (i.e., plastic hinge) of well-designed reinforced concrete frames are discussed, and equations to quantify each of them are proposed, as well as a methodology to incorporate them into a full displacement-based procedure for pre-earthquake and post-earthquake seismic assessment.

Research papers, The University of Auckland Library

Industrial steel storage pallet racking systems are used extensively worldwide to store goods. Forty percent of all goods are stored on storage racks at some time during their manufactureto- consumption life. In 2017, goods worth USD 16.5 billion were carried on cold-formed steel racking systems in seismically active regions worldwide. Historically, these racks are particularly vulnerable to collapse in severe earthquakes. In the 2010/2011 Christchurch earthquakes, around NZD 100 million of pallet racking stored goods were lost, with much greater associated economic losses due to disruptions to the national supply chain. A novel component, the friction slipper baseplate, has been designed and developed to very significantly improve the seismic performance of a selective pallet racking system in both the cross-aisle and the down-aisle directions. This thesis documents the whole progress of the development of the friction slipper baseplate from the design concept development to experimental verification and incorporation into the seismic design procedure for selective pallet racking systems. The test results on the component joint tests, full-scale pull-over and snap-back tests and fullscale shaking table tests of a steel storage racking system are presented. The extensive experimental observations show that the friction slipper baseplate exhibits the best seismic performance in both the cross-aisle and the down-aisle directions compared with all the other base-connections tested. It protects the rack frame and concrete floor from damage, reduces the risk of overturning in the cross-aisle direction, and minimises the damage at beam-end connectors in the down-aisle direction, without sustaining damage to the connection itself. Moreover, this high level of seismic performance can be delivered by a simple and costeffective baseplate with almost no additional cost. The significantly reduced internal force and frame acceleration response enable the more cost-effective and safer design of the pallet racking system with minimal extra cost for the baseplate. The friction slipper baseplate also provides enhanced protection to the column base from operational impact damage compared with other seismic resisting and standard baseplates.

Research papers, University of Canterbury Library

The lateral capacity of a conventional CLT shear wall is often governed by the strength and stiffness of its connections, which do not significantly utilize the in-plane strength of the CLT. Therefore, CLT shear walls are not yet being used efficiently in the construction of mass timber buildings due to a lack of research on high-capacity connections and alternative wall configurations. In this study, cyclic experiments were completed on six full-scale, 5-ply cantilever CLT shear walls with high-capacity hold-downs using mixed angle screws and bolts. All specimens exhibited significantly higher strength and stiffness than previously tested conventional CLT shear walls in the literature. The base connections demonstrated ductile failure modes through yielding of the hold-down connections. Based on the experimental results, numerical models were calibrated to investigate the seismic behaviour of CLT shear walls for prototype buildings of 3 and 6-storeys in Christchurch, NZ. As an alternative to cantilever (single) shear walls, a type of coupled wall with steel link beams between adjacent CLT wall piers was investigated. Effective coupling requires the link beam-to-wall connections to have adequate strength to ensure ductile link beam responses and adequate stiffness to yield the link beams at a relatively low inter-storey drift level. To this end, three beam-to-wall connection types were developed and cyclically tested to investigate their behaviour and feasibility. Based on the test results of the critical connection, a 3-storey, 2/3-scale coupled CLT wall specimen with three steel link beams and mixed angle screwed hold-downs was cyclically tested to evaluate its performance and experimentally validate the system concept. The test results showed a relatively high lateral strength compared to conventional CLT shear walls, as well as a high system ductility ratio of 7.6. Failure of the system was characterised by combined bending and withdrawal of the screws in the mixed angle screw hold-downs, yielding and eventual inelastic buckling of the steel link beams, CLT toe crushing, and local CLT delamination. Following the initial test, the steel link beams, mixed angle screw hold-downs, and damaged CLT regions were repaired, then the wall specimen was re-tested. The repaired wall behaved similarly to the original test and exhibited slightly higher energy dissipation and peak strength, but marginally more rapid strength deterioration under cyclic loading. Several hybrid coupled CLT shear walls were numerically modelled and calibrated based on the results of the coupled wall experiments. Pushover analyses were conducted on a series of configurations to validate a capacity design method for the system and to investigate reasonable parameter values for use in the preliminary design of the system. Additionally, an iterative seismic design method was proposed and used to design sample buildings of 6, 8, and 10-storeys using both nonlinear pushover and nonlinear time history analyses to verify the prototype designs. Results of the sample building analyses demonstrated adequate seismic behaviour and the proposed design parameters were found to be appropriate. In summary, high-capacity CLT shear walls can be used for the resistance of earthquakes by using stronger base connections and coupled wall configurations. The large-scale experimental testing in this study has demonstrated that both cantilever and coupled CLT shear walls are feasible LLRSs which can provide significantly greater lateral strength, stiffness, and energy dissipation than conventional CLT shear wall configurations.

Research papers, The University of Auckland Library

During the 2010/2011 Canterbury earthquakes, several reinforced concrete (RC) walls in multi-storey buildings formed a single crack in the plastic hinge region as opposed to distributed cracking. In several cases the crack width that was required to accommodate the inelastic displacement of the building resulted in fracture of the vertical reinforcing steel. This type of failure is characteristic of RC members with low reinforcement contents, where the area of reinforcing steel is insufficient to develop the tension force required to form secondary cracks in the surrounding concrete. The minimum vertical reinforcement in RC walls was increased in NZS 3101:2006 with the equation for the minimum vertical reinforcement in beams also adopted for walls, despite differences in reinforcement arrangement and loading. A series of moment-curvature analyses were conducted for an example RC wall based on the Gallery Apartments building in Christchurch. The analysis results indicated that even when the NZS 3101:2006 minimum vertical reinforcement limit was satisfied for a known concrete strength, the wall was still susceptible to sudden failure unless a significant axial load was applied. Additionally, current equations for minimum reinforcement based on a sectional analysis approach do not adequately address the issues related to crack control and distribution of inelastic deformations in ductile walls.

Research papers, University of Canterbury Library

Recent earthquakes in New Zealand proved that a shift is necessary in the current design practice of structures to achieve better seismic performance. Following such events, the number of new buildings using innovative technical solutions (e.g. base isolation, controlled rocking systems, damping devices, etc.), has increased, especially in Christchurch. However, the application of these innovative technologies is often restricted to medium-high rise buildings due to the maximum benefit to cost ratio. In this context, to address this issue, 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 a foundation system which will improve the seismic performance of medium-density low-rise buildings. Such foundation is characterized by two main elements: 1) granulated tyre rubber mixed with gravelly soils to be placed beneath the structure, with the goal of damping part of the seismic energy before it reaches the superstructure; and 2) a basement raft made of steel-fibre rubberised concrete to enhance the flexibility of the foundation under differential displacement demand. In the first part of this paper, the overarching objectives, scope and methodology of the project will be briefly described. Then, preliminary findings on the materials characterization, i.e., the gravel-rubber mixtures and steel-fibre rubberised concrete mixes, will be presented and discussed with focus on the mechanical behaviour.

Research papers, The University of Auckland Library

Reinforced concrete (RC) frame buildings designed according to modern design standards achieved life-safety objectives during the Canterbury earthquakes in 2010-11 and the Kaikōura earthquake in 2016. These buildings formed ductile plastic hinges as intended and partial or total building collapse was prevented. However, despite the fact that the damage level of these buildings was relatively low to moderate, over 60% of multi-storey RC buildings in the Christchurch central business district were demolished due to insufficient insurance coverage and significant uncertainty in the residual capacity and repairability of those buildings. This observation emphasized an imperative need to improve understanding in evaluating the post-earthquake performance of earthquake-damaged buildings and to develop relevant post-earthquake assessment guidelines. This thesis focuses on improving the understanding of the residual capacity and repairability of RC frame buildings. A large-scale five-storey RC moment-resisting frame building was tested to investigate the behaviour of earthquake-damaged and repaired buildings. The original test building was tested with four ground motions, including two repeated design-level ground motions. Subsequently, the test building was repaired using epoxy injection and mortar patching and re-tested with three ground motions. The test building was assessed using key concepts of the ATC-145 post-earthquake assessment guideline to validate its assessment procedures and highlight potential limitations. Numerical models were developed to simulate the peak storey drift demand and identify damage locations. Additionally, fatigue assessment of steel reinforcement was conducted using methodologies as per ATC-145. The residual capacity of earthquake-strained steel reinforcement was experimentally investigated in terms of the residual fatigue capacity and the residual ultimate strain capacity. In addition to studying the fatigue capacity of steel reinforcement, the fatigue damage demand was estimated using 972 ground motion records. The deformation limit of RC beams and columns for damage control was explored to achieve a low likelihood of requiring performance-critical repair. A frame component test database was developed, and the deformation capacity at the initiation of lateral strength loss was examined in terms of the chord rotation, plastic rotation and curvature ductility capacity. Furthermore, the proposed curvature ductility capacity was discussed with the current design curvature ductility limits as per NZS 3101:2006.

Images, UC QuakeStudies

Personnel from the USAID Disaster Assistance Response Team (DART) standing in Firefighters Reserve, in preparation for the two minutes of silence to honour the people who lost their lives in the 22 February 2011 earthquake. Just out of the picture is a sculpture fashioned from 5 tonnes of structural steel salvaged from the site of the World Trade Centre following their collapse on 11 September 2001 in terrorist attacks on New York City. The sculpture is now used as a tribute to firefighters in New Zealand.

Research papers, University of Canterbury Library

The NMIT Arts & Media Building is the first in a new generation of multistorey timber structures. It employs an advanced damage avoidance earthquake design that is a world first for a timber building. Aurecon structural engineers are the first to use this revolutionary Pres-Lam technology developed at the University of Canterbury. This technology marks a fundamental change in design philosophy. Conventional seismic design of multi-storey structures typically depends on member ductility and the acceptance of a certain amount of damage to beams, columns and walls. The NMIT seismic system relies on pairs of coupled LVL shear walls that incorporate high strength steel tendons post-tensioned through a central duct. The walls are centrally fixed allowing them to rock during a seismic event. A series of U-shaped steel plates placed between the walls form a coupling mechanism, and act as dissipators to absorb seismic energy. The design allows the primary structure to remain essentially undamaged while readily replaceable connections act as plastic fuses. In this era where sustainability is becoming a key focus, the extensive use of timber and engineered-wood products such as LVL make use of a natural resource all grown and manufactured within a 100km radius of Nelson. This project demonstrates that there are now cost effective, sustainable and innovative solutions for multi-story timber buildings with potential applications for building owners in seismic areas around the world.

Images, UC QuakeStudies

A protest sign painted on a fence shows an image of the cathedral spire and the words "Save + restore, stone by precious stone!" The photographer comments, "The Christchurch Cathedral got very badly damaged in the earthquake. It was being demolished down to a safe level before a major protest managed to stop it going too far. There is still an ongoing debate on what to do with the Cathedral. In the meantime a cardboard cathedral made out of a steel framework and massive toilet roll tubes is being constructed close by. This is to the right of the protest about the closure of Christchurch schools".

Images, Alexander Turnbull Library

Labour leader Phil Goff is being 'shored up' and strengthened by reinforced steel beams which represent his 'leadership. He tells ACT leader Rodney Hide who holds a newspaper with a headline reading 'ACT rattled again' that he needs to 'strengthen now before the next shake up!' As an insecure leader he is showing sympathy to Rodney Hide who is even more insecure because of the recent embarrassment of the David Garrett debacle. The title of the cartoon is 'Quake-proofing essential...' which is a reference to the Christchurch earthquake of 4th September and the continuing aftershocks. Quantity: 1 digital cartoon(s).

Research papers, University of Canterbury Library

Reconnaissance reports have highlighted the poor performance of non-ductile reinforced concrete buildings during the 2010-11 Canterbury earthquakes. These buildings are widely expected to result in significant losses under future earthquakes due to their seismic vulnerability and prevalence in densely populated urban areas. Wellington, for example, contains more than 70 pre-1970s multi-storey reinforced concrete buildings, ranging in height from 5 to 18 storeys. This study seeks to characterise the seismic performance and evaluate the likely failure modes of a typical pre-1970s reinforced concrete building in Wellington, by conducting advanced numerical simulations to evaluate its 3D nonlinear dynamic response. A representative 9-storey office building constructed in 1951 is chosen for this study and modelled in the finite element analysis programme DIANA, using a previously developed and validated approach to predict the failure modes of doubly reinforced walls with confined boundary regions. The structure consists of long walls and robust framing elements resulting in a stiff lateral load resisting system. Barbell-shaped walls are flanked by stiff columns with sufficient transverse reinforcement to serve as boundary regions. Curved shell elements are used to model the walls and their boundary columns, for which the steel reinforcement is explicitly modelled. Line elements are used to model the frame elements. The steel reinforcement in each member is explicitly modelled. The floor slabs are modelled using elastic shell elements. The model is analysed under short and long duration ground motions selected to match site specific targets in Wellington at the DBE and MCE intensity levels. The observed response of the building including drift profiles at each intesity level, strain localization effects around wall openings, and the influence of bidirectional loading are discussed.