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Research papers, University of Canterbury Library

During the past two decades, the focus has been on the need to provide communities with structures that undergo minimal damage after an earthquake event while still being cost competitive. This has led to the development of high performance seismic resisting systems, and advances in design methodologies, in order respect this demand efficiently. This paper presents the experimental response of four pre-cast, post-tensioned rocking wall systems tested on the shake-table at the University of Canterbury. The wall systems were designed as a retrofit solution for an existing frame building, but are equally applicable for use in new design. Design of the wall followed a performance-based retrofit strategy in which structural limit states appropriate to both the post-tensioned wall and the existing building were considered. Dissipation for each of the four post-tensioned walls was provided via externally mounted devices, located in parallel to post-tensioned tendons for re-centring. This allowed the dissipation devices to be easily replaced or inspected following a major earthquake. Each wall was installed with viscous fluid dampers, tension-compression yielding steel dampers, a combination of both or no devices at all – thus relying on contact damping alone. The effectiveness of both velocity and displacement dependant dissipation are investigated for protection against far-field and velocity-pulse ground motion characteristics. The experimental results validate the behaviour of ‘Advanced Flag-Shape’ rocking, dissipating solutions which have been recently proposed and numerically tested. Maximum displacements and material strains were well controlled and within acceptable bounds, and residual deformations were minimal due to the re-centring contribution from the post-tensioned tendons. Damage was confined to inelastic yielding (or fluid damping) of the external dampers.

Research papers, University of Canterbury Library

It is fast becoming common practice for civil engineering infrastructure and building structures to be designed to achieve a set of performance objectives. To do so, consideration is now being given to systems capable of sustaining minimal damage after an earthquake while still being cost competitive. This has led to the development of high performance seismic resisting systems, followed by advances in design methodologies. The paper presents the experimental response of four pre-cast, post-tensioned rocking walls with high-performing dissipating solutions tested on the shake-table at the University of Canterbury. The wall systems were designed as a retrofit solution for an existing frame building however, can also be used for the design of new, high-performance structures. The use of externally mounted dampers allowed numerous dissipation schemes to be explored including mild-steel dampers (hysteretic dampers), viscous dampers, a combination of both or no dampers. The advantages of both velocity and displacement dependant dissipation was investigated for protection against strong ground motions with differing rupture characteristics i.e. far-field and near-field events. The experimental results are used to verify a proposed design procedure for post-tensioned rocking systems with supplementary hysteretic and viscous dissipation. The predicted response compared well with the measured shake-table response.

Images, eqnz.chch.2010

Scavenger Hunt 101 - SH 8 (abandoned building or ruin) The ruins/remains of what was the third highest building in Christchurch, pre earthquakes, the Price Waterhouse Coopers building in Armagh Street. At 76.3 metres ( 21 floors) the demolition has left the basement (now flooded) and these supports. Just one of many photos from Christchurch ...

Images, eqnz.chch.2010

See previous photo (exactly 3 hours earlier). Demolition of the support structure for NZ Breweries smokestack in Christchurch. CERES NZ's nibbler is at work, the pipe stack having been removed yesterday (Saturday). This is three hours after the previous photo, and just a pile of rubble sits beside the tree (largely undamaged despite being next...

Images, eqnz.chch.2010

Went for a drive down to South New Brighton/Southshore after work today to see what interesting birds I could find on the Estuary (godwits, skuas, terns etc), but passing Jellico Street, I saw this. T-Rex the seismic survey truck from the University of Texas that is visiting the city (first time out of USA). Weighs 30 tonne and from the marks o...

Images, eqnz.chch.2010

The Cranmer Court demolition started today in Christchurch. The 1876 building was originally a Normal School and was in a derelict state in the early 1980s when it was rescued and converted into apartments. The heritage-listed building was red-stickered after the February 2011 earthquake.

Images, eqnz.chch.2010

Closeup of the Grand Chancellor showing the south eastern corner, which is where it has slumped and broken and is now leaning in that direction. I note that they have taken some equipment out of the roof, you can see daylight through the gaps on the other side. The broken windows are also clearly visible with curtains hanging in some of them. ...

Images, eqnz.chch.2010

There are occasional sewerage spills into the Avon River while all the sewer and road repairs are carried out. This rock wall was level and well above high tide level prior to the eathquakes. All the houses that can been seen here (except for those on the distant Port Hills) are in the suburban "red zone" and are still to be demolished.

Images, eqnz.chch.2010

20131214_6268_1D3-24 Where once stood houses (Day 348/365) The area beside the lower Avon River in New Brighton of Evans Avenue and Admirals Way has been cleared of houses and boundary fences (there were between 15 and 20 houses on this block) , fully fenced with post and wire and "spray on" grass applied. These were all red zone properties a...

Images, eqnz.chch.2010

Demolition of the support structure for NZ Breweries smokestack in Christchurch. CERES NZ's nibbler is at work, the pipe stack having been removed yesterday (Saturday). I retuned three hours later to see what progress had been made and it was GONE! See next photo. Damage to complex was from the 22/02/20011 earthquake.