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Images, UC QuakeStudies

A photograph of a severely-damaged building on Armagh Street. The building's facade has completely fallen away, and the bricks have fallen onto the footpath in front. USAR codes have been spray painted on an exposed wall.

Images, UC QuakeStudies

A photograph of the badly-damaged Edward Gibbon building on Tuam Street. The building has been cordoned off with wire fencing and the footpath behind the fence is covered in fallen bricks.

Images, UC QuakeStudies

A photograph of a badly-damaged building on the corner of Manchester Street and Gloucester Street. The top storey of the building has collapsed, and the bricks and wood have fallen onto the footpath below.

Images, UC QuakeStudies

A photograph of two workers walking down Gloucester Street. To the right, the earthquake-damaged Canterbury Times and Star Building can be seen. A car parked in front has been crushed by falling debris.

Images, UC QuakeStudies

A photograph of the badly-damaged Winnie Bagoes building on Colombo Street. The left side of the building has collapsed and a metal pole anchored to a concrete block is holding up the remains.

Images, UC QuakeStudies

A photograph of the badly-damaged Winnie Bagoes building on Colombo Street. The left side of the building has collapsed and a metal pole anchored to a concrete block is holding up the remains.

Images, UC QuakeStudies

A photograph of the earthquake damage to a building on Lichfield Street. The brick wall of the top storey of the building has crumbled, exposing the wooden structure underneath. Many of the windows are broken.

Images, UC QuakeStudies

A photograph of an earthquake damaged building on the corner of Manchester Street and Struthers Lane. The front wall of the building has crumbled, exposing the inside. One of the rooms is heavily graffitied.

Images, UC QuakeStudies

Detail of the partially-demolished Henry Africa's building. The photographer comments, "A building housing a restaurant and a great little neighbourhood bar is finally coming down because of earthquake damage. Henry's doorway. Still standing - the zebra striped doorway into Henry Africa's".

Images, UC QuakeStudies

A photograph of the badly-damaged Winnie Bagoes building on Colombo Street. The left side of the building has collapsed and a metal pole anchored to a concrete block is holding up the remains.

Images, UC QuakeStudies

Detail of the partially-demolished Henry Africa's building. The photographer comments, "A building housing a restaurant and a great little neighbourhood bar is finally coming down because of earthquake damage. Henry's doorway. Still standing - the zebra striped doorway into Henry Africa's".

Images, UC QuakeStudies

A photograph of the earthquake damage to the Base Packpackers building behind the former Canterbury Times building on Gloucester Street. The corner of Base Backpackers has collapsed, exposing a bunkroom inside. Scaffolding has been constructed up the side of the building.

Research papers, The University of Auckland Library

A review of the literature showed the lack of a truly effective damage avoidance solution for timber or hybrid timber moment resisting frames (MRFs). Full system damage avoidance selfcentring behaviour is difficult to achieve with existing systems due to damage to the floor slab caused by beam-elongation. A novel gravity rocking, self-centring beam-column joint with inherent and supplemental friction energy dissipation is proposed for low-medium rise buildings in all seismic zones where earthquake actions are greater than wind. Steel columns and timber beams are used in the hybrid MRF such that both the beam and column are continuous thus avoiding beam-elongation altogether. Corbels on the columns support the beams and generate resistance and self-centring through rocking under the influence of gravity. Supplemental friction sliders at the top of the beams resist sliding of the floor whilst dissipating energy as the floor lifts on the corbels and returns. 1:20 scale tests of 3-storey one-by-two bay building based on an earlier iteration of the proposed concept served as proof-of-concept and highlighted areas for improvement. A 1:5 scale 3-storey one-by-one bay building was subsequently designed. Sub-assembly tests of the beam-top asymmetric friction sliders demonstrated repeatable hysteresis. Quasi-static tests of the full building demonstrated a ‘flat bottomed’ flag-shaped hysteresis. Shake table tests to a suite of seven earthquakes scaled for Wellington with site soil type D to the serviceability limit state (SLS), ultimate limit state (ULS) and maximum credible event (MCE) intensity corresponding to an average return period of 25, 500 and 2500 years respectively were conducted. Additional earthquake records from the 22 February 2011 Christchurch earthquakes we included. A peak drift of 0.6%, 2.5% and 3.8% was reached for the worst SLS, ULS and MCE earthquake respectively whereas a peak drift of 4.5% was reached for the worst Christchurch record for tests in the plane of the MRF. Bi-directional tests were also conducted with the building oriented at 45 degrees on the shake table and the excitation factored by 1.41 to maintain the component in the direction of the MRF. Shear walls with friction slider hold-downs which reached similar drifts to the MRF were provided in the orthogonal direction. Similar peak drifts were reached by the MRF in the bi-directional tests, when the excitation was amplified as intended. The building self-centred with a maximum residual drift of 0.06% in the dynamic tests and demonstrated no significant damage. The member actions were magnified by up to 100% due to impact upon return of the floor after uplift when the peak drift reached 4.5%. Nonetheless, all of the members and connections remained essentially linearelastic. The shake table was able to produce a limited peak velocity of 0.275 m/s and this limited the severity of several of the ULS, MCE and Christchurch earthquakes, especially the near-field records with a large velocity pulse. The full earthquakes with uncapped velocity were simulated in a numerical model developed in SAP2000. The corbel supports were modelled with the friction isolator link element and the top sliders were modelled with a multi-linear plastic link element in parallel with a friction spring damper. The friction spring damper simulated the increase in resistance with increasing joint rotation and a near zero return stiffness, as exhibited by the 1:5 scale test building. A good match was achieved between the test quasi-static global force-displacement response and the numerical model, except a less flat unloading curve in the numerical model. The peak drift from the shake table tests also matched well. Simulations were also run for the full velocity earthquakes, including vertical ground acceleration and different floor imposed load scenarios. Excessive drift was predicted by the numerical model for the full velocity near-field earthquakes at the MCE intensity and a rubber stiffener for increasing the post joint-opening stiffness was found to limit the drift to 4.8%. Vertical ground acceleration had little effect on the global response. The system generates most of its lateral resistance from the floor weight, therefore increasing the floor imposed load increased the peak drift, but less than it would if the resistance of the system did not increase due to the additional floor load. A seismic design procedure was discussed under the framework of the existing direct displacement-based design method. An expression for calculating the area-based equivalent viscous damping (EVD) was derived and a conservative correction factor of 0.8 was suggested. A high EVD of up to about 15% can be achieved with the proposed system at high displacement ductility levels if the resistance of the top friction sliders is maximised without compromising reliable return of the floor after uplift. Uniform strength joints with an equal corbel length up the height of the building and similar inter-storey drifts result in minimal relative inter-floor uplift, except between the first floor and ground. Guidelines for detailing the joint for damage avoidance including bi-directional movement were also developed.

Images, eqnz.chch.2010

Our City building extensively propped up. File reference: CCL-2011-08-12-CanterburyPublic Library pre-demolition-040 From the collection of Christchurch City Libraries.