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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

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 large crack between a row of trees and the riverbank. A fence lining the riverbank has collapsed. The photographer comments, "On the 22 February 2011 we had an earthquake in Christchurch, which ripped us apart literally. This is what happened to the riverbank at New Brighton. Some trees stayed in place and others dropped 2 feet. The amazing thing was that they all stayed upright".

Images, UC QuakeStudies

A red sticker on the door of a damaged building in North New Brighton. The photographer comments, "A year after the earthquake in Christchurch a lot of buildings outside of the CBD are covered in cracks and beyond repair. These will slowly be demolished, but until then the buildings will be protected by a movable barrier and a red sticker".

Images, UC QuakeStudies

A car on Rowses Road has its wheels embedded in liquefaction. The photographer comments, "The most common sight was extensive damage to the roads. Papanui, Breezes, Wainoni, Shortland Street and many more roads had large cracks and large sink holes. There were approximately 6 cars and 1 large Ready Mix cement truck that had fallen into holes within a few blocks of each other. All people appear to have escaped without serious injury as far as I could tell".

Images, UC QuakeStudies

Detail of damage to the former Princess Cinema in New Brighton. Bricks have fallen from the wall, exposing the interior. The photographer comments, "This is the side view of the back of the old Princess Cinema in New Brighton after the earthquake in Christchurch, New Zealand on 22 February. The bricks seem to be just about to fall, but stayed in place after several big aftershocks. This building has now been knocked down as it was so dangerous".

Research papers, The University of Auckland Library

The susceptibility of precast hollow-core floors to sustain critical damage during an earthquake is now well-recognized throughout the structural engineering community in New Zealand. The lack of shear reinforcement in these floor units is one of the primary reasons causing issues with the seismic performance of these floors. Recent research has revealed that the unreinforced webs of these floor units can crack at drift demands as low as 0.6%. Such observation indicates that potentially many of the existing building stock incorporating hollow-core flooring systems in cities of relatively high seismic activity (e.g. Wellington and Christchurch) that probably have already experienced a level of shaking higher than 0.6% drift in previous earthquakes might already have their floor units cracked. However, there is little information available to reliably quantify the residual gravity load-carrying capacity of cracked hollow-core floor units, highlighting the need to understand the post-cracking behavior of hollow-core floor units to better quantify the extent of the risk that cracked hollow-core floor units pose.

Research papers, University of Canterbury Library

The performance of conventionally designed reinforced concrete (RC) structures during the 2011 Christchurch earthquake has demonstrated that there is greater uncertainty in the seismic performance of RC components than previously understood. RC frame and wall structures in the Christchurch central business district were observed to form undesirable cracks patterns in the plastic hinge region while yield penetration either side of cracks, and into development zones, were less than theoretical predictions. The implications of this unexpected behaviour: (i) significantly less available ductility; (ii) less hysteretic energy dissipation; and (iii) the localization of peak reinforcement strains, results in considerable doubt for the residual capacity of RC structures. The significance of these consequences has prompted a review of potential sources of uncertainty in seismic experimentation with the intention to improve the current confidence level for newly designed conventional RC structures. This paper attempts to revisit the principles of RC mechanics, in particular, to consider the influence of loading history, concrete tensile strength, and reinforcement ratio on the performance of ‘real’ RC structures compared to experimental test specimens.

Research papers, The University of Auckland Library

New Zealand’s stock of unreinforced masonry (URM) bearing wall buildings was principally constructed between 1880 and 1935, using fired clay bricks and lime or cement mortar. These buildings are particularly vulnerable to horizontal loadings such as those induced by seismic accelerations, due to a lack of tensile force-resisting elements in their construction. The poor seismic performance of URM buildings was recently demonstrated in the 2011 Christchurch earthquake, where a large number of URM buildings suffered irreparable damage and resulted in a significant number of fatalities and casualties. One of the predominant failure modes that occurs in URM buildings is diagonal shear cracking of masonry piers. This diagonal cracking is caused by earthquake loading orientated parallel to the wall surface and typically generates an “X” shaped crack pattern due to the reversed cyclic nature of earthquake accelerations. Engineered Cementitious Composite (ECC) is a class of fiber reinforced cement composite that exhibits a strain-hardening characteristic when loaded in tension. The tensile characteristics of ECC make it an ideal material for seismic strengthening of clay brick unreinforced masonry walls. Testing was conducted on 25 clay brick URM wallettes to investigate the increase in shear strength for a range of ECC thicknesses applied to the masonry wallettes as externally bonded shotcrete reinforcement. The results indicated that there is a diminishing return between thickness of the applied ECC overlay and the shear strength increase obtained. It was also shown that, the effectiveness of the externally bonded reinforcement remained constant for one and two leaf wallettes, but decreased rapidly for wall thicknesses greater than two leafs. The average pseudo-ductility of the strengthened wallettes was equal to 220% of that of the as-built wallettes, demonstrating that ECC shotcrete is effective at enhancing both the in-plane strength and the pseudo-ductility of URM wallettes. AM - Accepted Manuscript

Images, UC QuakeStudies

A pigeon perches in the beams of a damaged building. The photographer comments, "The building next door was demolished after the Christchurch earthquake, which exposed the side of this building with it's very old corrugated iron walls. Some of the sheeting was damaged and exposed parts of the interior. The pigeon was sitting on a bit of wood with the beam above it had a very serious crack. I think you would be nervous as well".

Images, UC QuakeStudies

A truck stuck in liquefaction on Breezes Road. The front wheels have fallen into a submerged pothole. The photographer comments, "The most common sight was extensive damage to the roads. Papanui, Breezes, Wainoni, Shortland Street and many more roads had large cracks and large sink holes. There were approximately 6 cars and 1 large Ready Mix cement truck that had fallen into holes within a few blocks of each other. All people appear to have escaped without serious injury as far as I could tell".

Images, UC QuakeStudies

Damage to River Road in Richmond. The road surface is badly cracked and slumped, and liquefaction silt covers part of the road. Two people in gumboots walk towards a barrier erected across the road using road cones and warning tape, and in the background the badly twisted Medway Street bridge can be seen. The photographer comments, "Longitudinal cracks indicate lateral movement as the land sagged towards the river. Near 373 River Rd, looking south-east towards Medway St. The Medway St bridge is visible in the background".

Images, UC QuakeStudies

Damage to a house in Richmond. The foundation is all that remains of one room, and the exposed interior wall has been covered with builders' paper for protection. Weeds grow between cracks in the concrete patio. The photographer comments, "Revisiting our abandoned house. Cracked patio. The wooden floor is all that remains of a sunny living space with bifold doors, opening the house to the garden. This was so broken on 4/9/10 that it was immediately demolished".

Research papers, University of Canterbury Library

Following the Mw 6.2 Christchurch Earthquake on 22 February 2011, extensive ground cracking in loessial soils was reported in some areas of the Port Hills, southeast of central Christchurch. This study was undertaken to investigate the mechanisms of earthquake-induced ground damage on the eastern side of the Hillsborough Valley. A zone of extensional cracking up to 40m wide and 600m long was identified along the eastern foot-slope, accompanied by compression features and spring formation at the toe of the slope. An engineering geological and geomorphological model was developed for the eastern Hillsborough Valley that incorporates geotechnical investigation data sourced from the Canterbury Geotechnical Database (CGD), the findings of trenching and seismic refraction surveying carried out for this research, and interpretation of historical aerial photographs. The thickness and extent of a buried peat swamp at the base of the slope was mapped, and found to coincide with significant compression features. Ground cracking was found to have occurred entirely within loess-colluvium and to follow the apices of pre-1920s tunnel-gully fan debris at the southern end of the valley. The ground-cracking on the eastern side of the Hillsborough Valley is interpreted to have formed through tensile failure of the loess-colluvium. Testing was carried out to determine the tensile strength of Port Hills loess colluvium as a function of water content and density, in order to better understand the occurrence and distribution of the observed ground cracking. A comprehensive review of the soil tensile strength testing literature was undertaken, from which a test methodology was developed. Results show remoulded loess-colluvium to possess tensile strength of 7 - 28 kPa across the range of tested moisture contents (10-15%) and dry densities (1650-1900kg/m3). A positive linear relationship was observed between tensile strength and dry density, and a negative linear relationship between moisture content and tensile strength. The observed ground damage and available geotechnical information (inclinometer and piezometer records provided by the Earthquake Commission) were together used to interpret the mechanism(s) of slope movement that occurred in the eastern Hillsborough Valley. The observed ground damage is characteristic of translational movement, but without the development of lateral release scarps, or a basal sliding surface - which was not located during drilling. It is hypothesised that shear displacement has been accommodated by multiple slip surfaces of limited extent within the upper 10m of the slope. Movement has likely occurred within near-saturated colluvial units that have lost strength during earthquake shaking. The eastern Hillsborough Valley is considered to be an ‘incipient translational slide’, as both the patterns of damage and shearing are consistent with the early stages of such slide development. Sliding block analysis was utilised to understand how the eastern Hillsborough Valley may perform in a future large magnitude earthquake. Known cumulative displacements of ~0.3m for eastern Hillsborough Valley during the 2010-2011 Canterbury Earthquake Sequence were compared with modelled slope displacements to back-analyse a lower-bound yield acceleration of 0.2 - 0.25g. Synthetic broadband modelling for future Alpine and Hope Fault earthquakes indicates PGAs of approximately 0.08g for soil sites in the Christchurch area, as such, slope movement is unlikely to be reactivated by an Alpine Fault or Hope Fault earthquake. This does not take into account the possible role of strength loss due to excess pore pressure that may occur during these future events.

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'.

Images, UC QuakeStudies

A photograph submitted by Gaynor James to the QuakeStories website. The description reads, "DTZ building going, 20 July 2011. A small crowd watches the demolition …There is an eerie silence- no excited buzz – people watching yet another part of their history turning into rubble. The wrecking ball, delicately positioned, drops and is followed by the cracking and rending of floor after floor and the debris tumbles down … It starts to clear and an extraordinary sight greets us. Hundreds and hundreds of sheets of paper drift down like giant confetti.".

Images, UC QuakeStudies

A photograph of a Wellington Emergency Management Office Emergency Response Team member talking to a member of the Professional Building Services on Gloucester Street. In the background is the Press House building with many cracks in the façade. Bits of bricks and other debris are scattered across the footpath. Some of the windows above the facade have broken. USAR codes have been spray-painted on one of the bottom-storey windows.

Images, UC QuakeStudies

A truck stuck in liquefaction on Breezes Road. The front wheels have fallen into a submerged pothole, and a digger is attempting to dig the truck out. The photographer comments, "The most common sight was extensive damage to the roads. Papanui, Breezes, Wainoni, Shortland Street and many more roads had large cracks and large sink holes. There were approximately 6 cars and 1 large Ready Mix cement truck that had fallen into holes within a few blocks of each other. All people appear to have escaped without serious injury as far as I could tell".

Images, UC QuakeStudies

A car stuck in liquefaction on Breezes Road. The front wheels have fallen into a submerged pothole, lifting the back wheels off the ground. The photographer comments, "The most common sight was extensive damage to the roads. Papanui, Breezes, Wainoni, Shortland Street and many more roads had large cracks and large sink holes. There were approximately 6 cars and 1 large Ready Mix cement truck that had fallen into holes within a few blocks of each other. All people appear to have escaped without serious injury as far as I could tell".

Images, UC QuakeStudies

A truck stuck in liquefaction on Breezes Road. The front wheels have fallen into a submerged pothole, and a digger is attempting to dig the truck out. The photographer comments, "The most common sight was extensive damage to the roads. Papanui, Breezes, Wainoni, Shortland Street and many more roads had large cracks and large sink holes. There were approximately 6 cars and 1 large Ready Mix cement truck that had fallen into holes within a few blocks of each other. All people appear to have escaped without serious injury as far as I could tell".

Images, UC QuakeStudies

The Cathedral of the Blessed Sacrament after the dome was removed. Large cracks are visible in the walls and in the dome's supporting structure, and the facade is supported by haybales and shipping containers. The photographer comments, "The main dome of the Cathedral of the Blessed Sacrament became unsafe after the February Christchurch earthquake - workmen have slowly been dismantling it. Now we are just left with the cracked and twisted walls that supported the beautiful dome".

Images, Alexander Turnbull Library

Prime Minister John Key sits at his desk on which are two baskets; the first is labelled 'Great news' and contains a very few documents and the second which is labelled 'Disasters' is so laden that it is causing the desk to crack. Context: New Zealand seems to be beset with disasters: the earthquakes in Christchurch, the 'Rena' shipwreck and consequeny oilspill etc. Quantity: 1 digital cartoon(s).

Images, Alexander Turnbull Library

The scene shows a tract of land with a jagged crack running through it. An arm representing the 'Council' reaches out of the crack and points a finger. Someone from the 'Tibetan Community' whose head cannot be seen says 'Surely you can lift finger higher than that?' Context: The Dalai Lama visited Christchurch after the earthquakes but The Dalai Lama's New Zealand representative is accusing the Christchurch City Council of snubbing the spiritual leader during his visit, suggesting ties with China are to blame. In a letter to Christchurch Mayor Bob Parker, New Zealand Tibetan community representative Thuten Kesang said he was disappointed the council "did not lift a finger to help" the Dalai Lama during his visit to the earthquake-hit city in June. Christchurch has a sister-city relationship with the Chinese Gansu Province and Wuhan City. Kesang said he believed this relationship made the council reluctant to engage with the exiled Tibetan leader. (Press - 10 August 2011) Quantity: 1 digital cartoon(s).

Images, UC QuakeStudies

Two men converse on the site of Gap Filler's "Film in the Gap!" project. Behind them is a chalkboard sign outlining the programme for the evening of April 2nd, 2011. The sign reads, "Gap Filler: 1st - 10th of April. Free live music and films from 6pm onwards. Saturday: 5pm: The Captain Willis Trio, 6pm: Ed Muzik, 7pm: The Cracks in Everything, 8pm: Film - 4 Houses, 4 Decades (Christchurch Architecture). All welcome! Bring a blanket or cushion. Ex demolition site. Please be safety aware. Proper footwear must be worn!".

Images, UC QuakeStudies

A car stuck in liquefaction on Breezes Road. The front wheels have fallen into a submerged pothole, lifting the back wheels off the ground. A line of other vehicles drive around the partially-submerged car. The photographer comments, "The most common sight was extensive damage to the roads. Papanui, Breezes, Wainoni, Shortland Street and many more roads had large cracks and large sink holes. There were approximately 6 cars and 1 large Ready Mix cement truck that had fallen into holes within a few blocks of each other. All people appear to have escaped without serious injury as far as I could tell".

Images, UC QuakeStudies

A car stuck in liquefaction on Breezes Road. The front wheels have fallen into a submerged pothole, lifting the back wheels off the ground. A line of other vehicles drive around the partially-submerged car. The photographer comments, "The most common sight was extensive damage to the roads. Papanui, Breezes, Wainoni, Shortland Street and many more roads had large cracks and large sink holes. There were approximately 6 cars and 1 large Ready Mix cement truck that had fallen into holes within a few blocks of each other. All people appear to have escaped without serious injury as far as I could tell".

Images, UC QuakeStudies

A photograph of the earthquake damage to the Avonmore House on the corner of Hereford Street and Latimer Square. Large cracks have formed in the building, causing sections of the masonry to crumble. The windows on the Hereford Street side of the building have bent out of shape and many of the glass panes have shattered. USAR codes have been spray painted on the column next to the door. In the distance wire fencing has been placed across the street as a cordon.

Research papers, University of Canterbury Library

A building boom in the 1980s allowed pre-stressed hollow-core floor construction to be widely adopted in New Zealand, even though the behaviour of these prefabricated elements within buildings was still uncertain. Inspections following the Canterbury and Kaikōura earthquakes has provided evidence of web-splitting, transverse cracking and longitudinal splitting on hollow-core units, confirming the susceptibility of these floors to undesirable failure modes. Hollow-core slabs are mainly designed to resist bending and shear. However, there are many applications in which they are also subjected to torsion. In New Zealand, hollow-core units contain no transverse reinforcement in the soffit concrete below the cells and no web reinforcement. Consequently, their dependable performance in torsion is limited to actions that they can resist before torsional cracking occurs. In previous work by the present authors, a three-dimensional FE modelling approach to study the shear flexural behaviour of precast pre-stressed hollow core units was developed and validated by full-scale experiments. This paper shows how the FE analyses have been extended to investigate the response of HC units subjected to torsional actions. Constitutive models, based on nonlinear fracture mechanics, have been used to numerically predict the torsional capacity of HC units and have been compared with experimental results. The results indicate that the numerical approach is promising and should be developed further as part of future research.