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Images, UC QuakeStudies

A view across London Street in Lyttelton to the Empire Hotel and the Lyttelton Bakery. The buildings have been cordoned off by a safety fence and the facade of the Empire Hotel has been braced with steel beams.

Images, UC QuakeStudies

A view across London Street in Lyttelton to the Empire Hotel and the Lyttelton Bakery. The buildings have been cordoned off by a safety fence. Sections of the side wall of the Empire Hotel have crumbled and its facade has been braced with steel beams.

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 Cranmer Centre on Armagh Street. Bricks have fallen off one of the gables onto the concrete below. The remaining gables have been braced with wood to limit further damage. A cherry picker can be seen below, and there is fencing around the building.

Images, UC QuakeStudies

The southern side of the Christ Church Cathedral with boarded up windows and damage to the roof above both of the transepts. Damaged masonry has been piled on the ground in front and one of the spires has been removed and braced with steel in the foreground.

Images, UC QuakeStudies

Damage to the wall around a circular window inside the Durham Street Methodist Church. The plaster around the window is badly cracked and has chipped away in some sections, revealing the brickwork underneath it. The window has been weather proofed with plywood and braced with planks of wood.

Images, UC QuakeStudies

A photograph of the north side of the ChristChurch Cathedral with the Citizen's Memorial to the left. The roof of the cathedral has been damaged, and many of the doors and windows boarded up. On the memorial, the angel's waist and neck have been braced to keep her standing.

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. A red sticker on the door indicates that the building is unsafe to enter.

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

The west-side of the Arts Centre along Rolleston Avenue near the entrance to the Botanic Gardens. Wire fencing and road cones have been placed around the building as a cordon. To the left, a crane is parked next to the building. The spire has been removed and braced on the footpath to limit damage.

Images, UC QuakeStudies

Damage to the Visitors Centre in Kaiapoi, after the September 4th earthquake. The foundations have lifted at the back of the building, giving it a forward lean. Cables have been attached to the balcony over the walkway and braced to posts cemented into the ground. This is to stop the building from slumping further.

Images, UC QuakeStudies

Damage to the Visitors Centre in Kaiapoi, after the September 4th earthquake. The foundations have lifted at the back of the building, giving it a forward lean. Cables have been attached to the balcony over the walkway and braced to posts cemented into the ground. This is to stop the building from slumping further.

Images, UC QuakeStudies

A sign on the door of a shop reading, "I have been reclosed again by the Council due to buckled retaining wall in basement. My landlord is getting wall braced for all our safety. I hope to reopen in 2/3 weeks. I will try and keep you informed by note on shop glass. Ross".

Images, UC QuakeStudies

A damaged building on Cashel Street near Oxford Terrace. The top of the facade has fallen off the building into the street below, taking the awning with it. Bricks from the building still lie on the footpath where they fell. Above, the windows have been braced with plywood. Wire fencing has been placed around the building as a cordon.

Images, UC QuakeStudies

A photograph of the earthquake damage to the Christchurch Chinese Methodist Church on Papanui Road. The gable walls have crumbled, bricks spilling onto the ground. The tower has been removed and braced on the ground in front. Cordon fencing has been placed around the building. Parts of the fence have been decorated with hearts and the word 'love'.

Images, UC QuakeStudies

A photograph of an earthquake-damaged building in Christchurch. The wall on the side of the house has crumbled, and the bricks have fallen onto the fence and damaged it. Wooden planks have been used to brace the wall towards the back of the property. A red sticker on the front window indicates that the house is unsafe to enter.

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 looking south down Colombo Street from the intersection of Gloucester Street. In the distance a crane is hanging over Cathedral Square. Below the crane is a pile of rubble from the partially-demolished tower of ChristChurch Cathedral. To the right is a smaller crane and a steel structure which will be used to brace the front of the Cathedral.

Images, UC QuakeStudies

One end of the Arts Centre photographed shortly after the 22 February 2011 earthquake. The gable of the building has crumbled and fallen to the ground, collapsing an awning. A large crack can be seen in the corner tower. Blue ties can be seen at the top of the tower, used to brace the structure after the 4 September 2010. This has probably limited the damage caused by the 22 February 2011 earthquake.

Images, UC QuakeStudies

The north-west end of the Arts Centre on the corner of Rolleston Avenue and Worcester Boulevard. The tip of the gable is missing as well as the spire which has been removed and braced on the footpath to limit damage. Wire fencing and road cones have been placed around the building as a cordon. In the distance, a crane is working on the building.

Images, UC QuakeStudies

The Arts Centre photographed shortly after the 22 February 2011 earthquake. A large crack can be seen in the tower and part of the brickwork around the clock has collapsed onto the pavement below. Scaffolding was placed up against the building after the 4 September 2010 earthquake and the gable was braced with wooden planks. This probably limited the damage to this part of the building. The building has been cordoned off with tape reading, 'Danger keep out'. A sign in front of the door reads, 'Site closed'.

Research papers, The University of Auckland Library

A non-destructive hardness testing method has been developed to investigate the amount of plastic strain demand in steel elements subjected to cyclic loading. The focus of this research is on application to the active links of eccentrically braced frames (EBFs), which are a commonly used seismic-resisting system in modern steel framed buildings. The 2010/2011 Christchurch earthquake series, especially the very intense February 22 shaking, which was the first earthquake worldwide to push complete EBF systems fully into their inelastic state, generating a moderate to high level of plastic strain in EBF active links, for a range of buildings from 3 to 23 storeys in height. This raised two important questions: 1) what was the extent of plastic deformation in active links; and 2) what effect does that have to post-earthquake steel properties? This project comprised determining a robust relationship between hardness and plastic strain in order to be able to answer the first question and provide the necessary input into answering the second question. A non-destructive Leeb (portable) hardness tester (model TH170) has been used to measure the hardness, in order to determine the plastic strain, in hot rolled steel universal sections and steel plates. A bench top Rockwell B was used to compare and validated the hardness measured by the portable hardness tester. Hardness was measured from monotonically strained tensile test specimens to identify the relationship between hardness and plastic strain demand. Test results confirmed a good relationship between hardness and the amount of monotonically induced plastic strain. Surface roughness was identified as an important parameter in obtaining reliable hardness readings from a portable hardness reader. A proper surface preparation method was established by using three different cleaning methods, finished with hand sanding to achieve surface roughness coefficients sufficiently low not to distort the results. This work showed that a test surface roughness (Ra) is not more than 1.6 micron meter (μm) is required for accurate readings from the TH170 tester. A case study on an earthquake affected building was carried out to identify the relationship between hardness and amount of plastic strain demand in cyclically deformed active links. Hardness was carried out from active links shown visually to have been the most affected during one of the major earthquake events. Onsite hardness test results were then compared with laboratory hardness test results. A good relationship between hardness from onsite and laboratory was observed between the test methods; Rockwell B bench top and portable Leeb tester TH170. Manufacturing induced plastic strain in the top and bottom of the webs of hot rolled sections were discovered from this research, an important result which explains why visual effects of earthquake induced active link yielding (eg cracked or flaking paint) was typically more prevalent over the middle half depth of the active link. The extent of this was quantified. It was also evident that the hardness readings from the portable hardness tester are influenced by geometry, mass effects and rigidity of the links. The final experimental stage was application of the method to full scale cyclic inelastic tested nominally identical active links subjected to loading regimes comprising constant and variable plastic strain demands. The links were cyclically loaded to achieve different plastic strain level. A novel Digital Image Correlation (DIC) technique was incorporated during the tests of this scale, to confirm the level of plastic strain achieved. Tensile test specimens were water jet cut from cyclically deformed webs to analyse the level of plastic strain. Test results show clear evidence that cyclically deformed structural steel elements show good correlation between hardness and the amount of plastic strain demand. DIC method was found to be reliable and accurate to check the level of plastic strain within cyclically deformed structural steel elements.

Research papers, The University of Auckland Library

Eccentrically Braced Frames (EBFs) are a widely used seismic resisting structural steel system. Since their inception in the late 1970s, they have been a viable option with an available stiffness that is between simple braced systems and moment resisting systems. A similar concept, the linked column frame (LCF), uses shear links between two closely spaced columns. In both cases, the key component is the active link or the shear link, and this component is the objective of this study. The performance of high rise EBF buildings in the 2010 and 2011 Christchurch earthquakes was beyond that which was expected, especially considering the very high accelerations recorded. As the concrete high-rises were torn down, two EBF buildings remained standing and only required some structural repair. These events prompted a renewed interest in bolted shear links, as well as their performance. While some research into replaceable shear links had already been done (Mansour, 2011), the objectives of this study were to improve on the shear link itself, with the consideration that links built in the future are likely to be bolted. The main components of this study were to: 1. Reduce or eliminate the requirements for intermediate web stiffeners, as they were suspected of being detrimental to performance. Furthermore, any reduction in stiffening requirements is a direct fabrication cost saving. Links with low web aspect ratios were found to achieve exceptional ductilities when no stiffeners were included, prompting new design equations. 2. Ensure that the stresses in the ends of links are adequately transferred into the endplates without causing fractures. Although most of the experimental links had web doubler plates included, four had varied lengths of such doubler plates from 0.0 in. to 8.0 in. The link without any doubler plates performed to a similar level to its peers, and thus it is likely that links with quality end details may not need web doubler plates at all. 3. Evaluate the performance of a link with double sided stiffeners without the use of web welds, as opposed to conventional single sided, welded stiffeners. This link performed well, and web-weld-less double sided stiffeners may be an economical alternative to conventional stiffeners for deeper sections of links. 4. Evaluate the performance of a link with thin endplates that are made efficient with the use of gusset plates. This link performed to an acceptable level and provides evidence for a cost effective alternative to thick endplates, especially considering the high overstrength end moments in links, typically requiring 16-bolt connections. 5. Examine the potential use of an alternative EBF arrangement where the collector beam is over sized, and the link section is formed by cutting out parts of the beam's web. After running a series of finite element models each with a unique variation, a number of approximate design rules were derived such that future research could develop this idea further experimentally. 6. Ensure that during testing, the secondary elements (members that are not the shear link), do not yield and are not close to yielding. None of the instrumented elements experienced any unexpected yielding, however the concerns for high stresses in the collector beam panel zone during design were warranted. The use of an existing New Zealand design equation is recommended as an extra check for design codes worldwide. The above objectives were mainly conducted experimentally, except: the data set for item 1 was greatly expanded through the use of a calibrated numerical model which was then used in an extensive parametric study; item 5 was purely finite element based; and, a small parametric study was included for item 3 in an attempt to expand on the trends found there.