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Images, UC QuakeStudies

A photograph of the earthquake damage to a house on Bealey Avenue near Springfield Road. The walls have crumbled, the bricks spilling onto the footpath in front. the ceiling of the building has been braced with scaffolding. A red sticker on the door indicates that the building is unsafe to enter.

Images, UC QuakeStudies

The Wizard of Christchurch talks to people viewing the damaged Christ Church Cathedral. Bracing has been placed against the front wall to limit further damage. A walkway from Gloucester Street to the Square was opened up for a few days to allow the public a closer look.

Images, UC QuakeStudies

Damage to the front of Christ Church Cathedral. The tower has been damaged and bracing has been placed on the front wall (right) to limit further damage. A walkway from Gloucester Street to the Square was opened up for a few days to allow the public a closer look.

Images, UC QuakeStudies

The side of the Empire Hotel on London Street in Lyttelton where the brick wall has crumbled. Bracing has been placed on the front of the building to keep it together and limit further damage from aftershocks. The building has been cordoned off with fencing.

Images, UC QuakeStudies

A view across Wakefield Avenue in Sumner to several local businesses, including Sumner Asian Restaurant, KB's Bakery, Harcourt's and The Ruptured Duck Pizzeria and Bar. Metal pipes can be seen bracing the balcony and walls of the building housing Harcourt's and The Ruptured Duck. The building has been cordoned off by a safety fence, and large cracks are visible in its walls and cornice.

Images, UC QuakeStudies

A photograph of the earthquake damage to a house on Bealey Avenue near Springfield Road. The walls have crumbled, the bricks spilling onto the footpath in front. the ceiling of the building has been braced with scaffolding. Wire fencing and police tape has been placed around the building as a cordon.

Images, UC QuakeStudies

A photograph of the earthquake damage to a house on Bealey Avenue near Springfield Road. The walls have crumbled, the bricks spilling onto the footpath in front. the ceiling of the building has been braced with scaffolding. Wire fencing and police tape has been placed around the building as a cordon.

Images, UC QuakeStudies

A photograph of the earthquake damage to a house on Bealey Avenue near Springfield Road. The walls have crumbled, the bricks spilling onto the footpath in front. The ceiling of the building has been braced with scaffolding. Wire fencing and police tape has been placed around the building as a cordon.

Images, UC QuakeStudies

Members of the public view the damaged tower of Christ Church Cathedral. Bracing has been placed on the front wall to the right to limit further damage. In the centre of the crowd stands a wire cage filled with stones. After the earthquake, love notes to Christchurch were written on the stones.

Images, UC QuakeStudies

A damaged brick building has wooden bracing holding the walls together. The photographer comments, "This building came through the September Christchurch quake with a few band aid plasters, but the February quake means that she is now DNR (Do Not Resuscitate)".

Images, UC QuakeStudies

A panoramic photograph taken at the front of Christ Church Cathedral. The front of the cathedral has steel bracing against it to limit further damage. The upper part of the front wall has crumbled completely, exposing the inside space. The Chalice sculpture is to the right and the BNZ building can be seen in the background.

Images, UC QuakeStudies

The McKenzie and Willis building on High Street with damage to the top storey. The side wall has crumbled, exposing the inside of the building where the roof has been propped up by scaffolding. The front facade of the building is also damaged and is held upright by steel bracing.

Images, UC QuakeStudies

The front of Christ Church Cathedral. The upper part of the front wall has crumbled leaving the inside space exposed. Steel bracing has been placed against it to limit further damage. 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.

Images, UC QuakeStudies

Damage to the front gable of the Durham Street Methodist Church. Masonry has fallen from the top of the gable, and the resulting gap has been weather proofed with plywood, tarpaulins and metal tiles. The steel bracing propping the whole front wall can be seen at the bottom of the photograph.

Images, UC QuakeStudies

A photograph of the clock tower of the former railway station building on Moorhouse Avenue. A crane is lifting two men in a basket up the side of the tower. Plywood has been placed around the walls as bracing. A sign sponsored by The Press is attached to the plywood, and holds messages from the community.

Images, UC QuakeStudies

The front of Christ Church Cathedral showing its broken tower. Bracing has been placed on the front wall to limit further damage. Security fences have been placed around the cathedral to restrict access. The Wizard of Christchurch talks to members of the public. A walkway from Gloucester Street to the Square was opened up for a few days to allow the public a closer look.

Images, UC QuakeStudies

The front of Christ Church Cathedral showing its broken tower. Bracing has been placed on the front wall to limit further damage. Security fences have been placed around the cathedral to restrict access. The Wizard of Christchurch talks to members of the public. A walkway from Gloucester Street to the Square was opened up for a few days to allow the public a closer look.

Research papers, University of Canterbury Library

The ultimate goal of this study is to develop a model representing the in-plane behaviour of plasterboard ceiling diaphragms, as part of the efforts towards performance-based seismic engineering of low-rise light timber-framed (LTF) residential buildings in New Zealand (NZ). LTF residential buildings in NZ are constructed according to a prescriptive standard – NZS 3604 Timberframed buildings [1]. With regards to seismic resisting systems, LTF buildings constructed to NZS3604 often have irregular bracing arrangements within a floor plane. A damage survey of LTF buildings after the Canterbury earthquake revealed that structural irregularity (irregular bracing arrangement within a plane) significantly exacerbated the earthquake damage to LTF buildings. When a building has irregular bracing arrangements, the building will have not only translational deflections but also a torsional response in earthquakes. How effectively the induced torsion can be resolved depends on the stiffness of the floors/roof diaphragms. Ceiling and floor diaphragms in LTF buildings in NZ have different construction details from the rest of the world and there appears to be no information available on timber diaphragms typical of NZ practice. This paper presents experimental studies undertaken on plasterboard ceiling diaphragms as typical of NZ residential practice. Based on the test results, a mathematical model simulating the in-plane stiffness of plasterboard ceiling diaphragms was developed, and the developed model has a similar format to that of plasterboard bracing wall elements presented in an accompany paper by Liu [2]. With these two models, three-dimensional non-linear push-over studies of LTF buildings can be undertaken to calculate seismic performance of irregular LTF buildings.

Research papers, University of Canterbury Library

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.