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Bond and shear mechanics within reinforced concrete beam-column joints inc…
Research papers, University of Canterbury Library
The recent earthquakes in Christchurch have made it clear that issues exist with current RC frame design in New Zealand. In particular, beam elongation in RC frame buildings was widespread and resulted in numerous buildings being rendered irreparable. Design solutions to overcome this problem are clearly needed, and the slotted beam is one such solution. This system has a distinct advantage over other damage avoidance design systems in that it can be constructed using current industry techniques and conventional reinforcing steel. As the name suggests, the slotted beam incorporates a vertical slot along part of the beam depth at the beam-column interface. Geometric beam elongation is accommodated via opening and closing of these slots during seismically induced rotations, while the top concrete hinge is heavily reinforced to prevent material inelastic elongation. Past research on slotted beams has shown that the bond demand on the bottom longitudinal reinforcement is increased compared with equivalent monolithic systems. Satisfying this increased bond demand through conventional means may yield impractical and economically less viable column dimensions. The same research also indicated that the joint shear mechanism was different to that observed within monolithic joints and that additional horizontal reinforcement was required as a result. Through a combination of theoretical investigation, forensic analysis, and database study, this research addresses the above issues and develops design guidelines. The use of supplementary vertical joint stirrups was investigated as a means of improving bond performance without the need for non-standard reinforcing steel or other hardware. These design guidelines were then validated experimentally with the testing of two 80% scale beam-column sub-assemblies. The revised provisions for bond within the bottom longitudinal reinforcement were found to be adequate while the top longitudinal reinforcement remained nominally elastic throughout both tests. An alternate mechanism was found to govern joint shear behaviour, removing the need for additional horizontal joint reinforcement. Current NZS3101:2006 joint shear reinforcement provisions were found to be more than adequate given the typically larger column depths required rendering the strut mechanism more effective. The test results were then used to further refine design recommendations for practicing engineers. Finally, conclusions and future research requirements were outlined.
BeckerFraserPhotos November 2010 photograph 33
Images, UC QuakeStudies
A damaged property on Avonside Drive. Cracks can be seen running through the lawn. A woman is standing on a slab of concrete that has been raised by the earthquake.
BeckerFraserPhotos May 2011 photograph 0090
Images, UC QuakeStudies
The entrance to the central Library on Gloucester Street has been boarded up and USAR codes have been spray-painted on the concrete pillar. A 'Library open' sign remains outside.
BeckerFraserPhotos February 2012 photograph 0171
Images, UC QuakeStudies
A photograph of a train painted on a concrete block in a retaining wall, alongside the words, "The gravy train". The photograph is captioned by BeckerFraserPhotos, "Cunningham Terrace, Lyttelton".
BeckerFraserPhotos February 2012 photograph 0176
Images, UC QuakeStudies
A photograph of an opera singer singing the words "Cera, cera", painted on a concrete block in a retaining wall. The photograph is captioned by BeckerFraserPhotos, "Cunningham Terrace, Lyttelton".
Paul and Sam Corliss's Street Art Photograph (2015:03:27 12:52:56)
Images, UC QuakeStudies
A photograph of a tag on a wall made of concrete blocks. The wall is near the railway tracks which run under the Durham Street over bridge. The tag reads, "JFK".
BeckerFraserPhotos December 2011 photograph 1971
Images, UC QuakeStudies
A photograph captioned by BeckerFraserPhotos, "A concrete-block wall from a building on the corner of Colombo and Gloucester Streets which has fallen in an interesting pattern during demolition".
Grand Chancellor Lean
Images, eqnz.chch.2010
Hotel Grand Chancellor on verge of collapse but still standing after the 6.3 magnitude quake hit Christchurch on 22 February 2011 because of concrete being poured into the lower floors.
Effect of precast-prestressed flooring systems on the seismic performance …
Research papers, University of Canterbury Library
A one story, two bays, approximately half scaled, perimeter moment frame containing precastprestressed floor units was built and tested at the University of Canterbury to investigate the effect of precastprestressed floor units on the seismic performance of reinforced concrete moment resisting frame. This paper gives an overview of the experimental set up and summarizes the results obtained from the test. The results show that elongation in the beam plastic hinges is partially restrained by the prestressed floor, which increases the strength of the beams much more than that being specified in the codes around the world.
BeckerFraserPhotos February 2012 photograph 0169
Images, UC QuakeStudies
A photograph of a house with retaining walls supported by large bags of concrete. The photograph is captioned by BeckerFraserPhotos, "On the corner of Ticehurst Road and Bridle Path, Lyttelton".
BeckerFraserPhotos May 2013 photograph 173
Images, UC QuakeStudies
A temporary retaining wall on Sumner Road in Lyttelton. The concrete moulds for the wall are filled with rocks and stones. Black tarpaulins have been placed over the top section of the wall.
Umut Akguzel Photograph 367
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.
Bettina Evans's photograph 100
Images, UC QuakeStudies
Patchwork quilts wrapped around the concrete slabs used to stabilise a broken wall on Winchester Street. They make it look snug despite the snow. Many projects like this have cropped up around Canterbury in an effort to brighten the earthquake environment.
Umut Akguzel Photograph 366
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.
BeckerFraserPhotos July 2011 photograph 1316
Images, UC QuakeStudies
A photograph captioned by BeckerFraserPhotos, "Victoria Street. A giant vibrating pair of nibblers makes easy work of demolishing a reinforced concrete building. This section of wall was reduced to rubble in about two minutes".
BeckerFraserPhotos April 2011 photograph 015
Images, UC QuakeStudies
Plastic barriers and fencing around a demolition site on the corner of Cranford and Westminster Streets. Different types of building rubble have been sorted into piles, and a concrete block still remains on-site.
BeckerFraserPhotos February 2011 photograph 340
Images, UC QuakeStudies
Two damaged driveways on Acland Avenue in Avonside. Dried liquefaction can be seen in the gap between the two driveways, and behind them the ground has sunk. Weeds have grown through cracks in the concrete.
BeckerFraserPhotos October 2011 photograph 356
Images, UC QuakeStudies
Photograph captioned by BeckerFraserPhotos, "Demolition site of Allan McLean building, corner of Colombo Street and Oxford Terrace".
BeckerFraserPhotos February 2011 photograph 339
Images, UC QuakeStudies
Two damaged driveways on Acland Avenue in Avonside. Dried liquefaction can be seen in the gap between the two driveways, and behind them the ground has sunk. Weeds have grown through cracks in the concrete.
Photograph of Gap Filler project 22 (12)
Images, UC QuakeStudies
The partially constructed Pallet Pavilion on the site of the demolished Crowne Plaza Hotel. Concrete slabs have been laid on the ground and a stack of painted pallets can be seen in the background.
Photograph by Jocelyn Kinghorn 2391
Images, UC QuakeStudies
Damage to the Cathedral of the Blessed Sacrament. Looking through the fence on to the side and front where shipping containers are being used to support the walls, with a pile of concrete blocks next to the cathedral.
Crack'd for Christchurch Photograph 112
Images, UC QuakeStudies
A photograph of Marie Hudson attaching a flower mosaic to Crack'd for Christchurch's armchair artwork.Crack'd for Christchurch comments, "Marie makes it look easy."
Crack'd for Christchurch Photograph 111
Images, UC QuakeStudies
A photograph of Marie Hudson attaching a flower mosaic to Crack'd for Christchurch's armchair artwork.Crack'd for Christchurch comments, "Marie makes it look easy."
BeckerFraserPhotos February 2011 photograph 268
Images, UC QuakeStudies
A view down Bracken Street in Avonside. A power pole has been propped up by a concrete block because the asphalt around it has sunk as a result of the 4 September 2010 earthquake.
BeckerFraserPhotos June 2011 photograph 370
Images, UC QuakeStudies
Damage to a house in Redcliffs. There are large cracks in the concrete block walls and several blocks have fallen. The chimney is still intact, but is leaning away from the house at an extreme angle.
BeckerFraserPhotos June 2011 photograph 371
Images, UC QuakeStudies
Damage to a house in Redcliffs. There are large cracks in the concrete block walls and several blocks have fallen. The chimney is still intact, but is leaning away from the house at an extreme angle.
BeckerFraserPhotos February 2011 photograph 405
Images, UC QuakeStudies
A view down the driveway of a property on Avonside Drive to its garage. The slabs of concrete that make up the driveway have all visibly shifted, and the garage is on a lean.
Photograph by Neil Macbeth 357
Images, UC QuakeStudies
Damage to a bridge over the Avon River in Avonside. The bridge has pulled away from the bank, leaving large cracks between the concrete sides and the ground. The railing has also separated to the left.
BeckerFraserPhotos June 2012 photograph 451
Images, UC QuakeStudies
Photograph captioned by BeckerFraserPhotos, "A view of High Street, looking across Cashel Street towards Te Waipounamu in Hereford Street with the huge pile of concrete rubble from the Hotel Grand Chancellor".
BeckerFraserPhotos April 2012 photograph 228
Images, UC QuakeStudies
Colombo Street looking south from Kilmore Street. Concrete and wire fencing have been placed over the street as a cordon. In the distance, the bracing in front of the Cathedral can be seen.