Earthquake protection wins top concrete award
Innovative technology designed to reduce seismic damage won the 2009 premiere New Zealand Concrete Society Award.
The Alan MacDiarmid Building at the Victoria University of Wellington won the society’s Technology Award and also took out supreme winner of the Concrete Society’s biennial Concrete Award. It is the first multi-storey building in the country to include unbounded post-tensioned tendons and rocking joints that are an enhanced version of the US-based Precast Seismic Structural Systems (PRESSS) research.
The system uses un-bonded, post-tensioning and rocking joints within the structure to ensure the building returns to upright without significant structural damage, even after a major earthquake.
The use of capping beans beams above rocking shear walls and replaceable mild-steel energy dissipaters located at beam-column joints are world first.
The building is made up of four suspended floors of science teaching and research space.
The judges say it is fitting that the building, named after an eminent Nobel Prize-winning scientist, should incorporate such cutting-edge technology. Convenor of judges Andrew Charleson says important aspects of the technology were refined and enhanced in the design that underwent several peer reviews.
“In the event of an earthquake, not only will the likelihood of damage to the structure be reduced, but the fit-out and scientific equipment in the building will also be protected.”
The award entrant was Dunning Thorton Consultants and the contractor was Mainzeal.
Viaduct infrastructure awarded
The three kilometre Tauranga Harbour Link: Stage 2, took out the Infrastructure Award. This 560 metre long (and up to 40 metre wide) stretch of motorway is made up of four concrete structures that cross several roads and railways lines.
To overcome these obstructions, vertical clearances and numerous site constraints, an optimum pier spacing was determined – that was beyond the accepted limit for simply supported 1500mm deep tee-roll beams with conventional strand. The solution was to design the beams with a mixture of pre and post-tensioned tendons.
This combination optimised the beam design while still allowing daily casting cycles in the precast yard.
The project involved such innovations as the large diameter and deep bored piling under bentonite, post-tensioning of standard pre-tensioned beams to extend their span and load capacity, and precautions to ensure durability in the marine environment.
Instrumentation was installed in some bridge beams to monitor chloride ingress. The launching method of the new bridge proved effective given the attractively curved bridge and the accuracy of its final positioning, say the judges.
The entrant and contractor was Fletcher Construction Company.
Bridge appeal and functionality commended
Commended in the Infrastructure Award was the Ormiston Road cable-stayed bridge in Manukau, entered by Fulton Hogan and Beca.
Two concrete pylons are the main visual elements of this bridge, the gateway to newly-planned Flatbush township. The casting of the pylons was challenging, however meticulous planning and the use of self-compacting concrete achieved a quality finish, say the judges.
“The casting of the 45 metre high transversely and longitudinally inclined pylon was a significant challenge.
“However, with meticulous design and construction planning, and application of self-compacting concrete under a 28 metre pressure head, a high quality surface finish to this iconic structure was achieved: a celebration of concrete in compression.”
Innovative rock wall
An imitation basalt rock wall for the side of a motorway took out the Landscaping Award. The State Highway 20 Walmsley off ramp rock wall is part of the Manukau Harbour Crossing being built for the NZ Transport Agency by the Manukau Harbour Crossing Alliance.
The contract called for the retaining wall on the Walmsley Road south-bound off-ramp to feature a soil nail retaining wall finished with patterned pre-cast panels.
The medium size of the wall and some design features that did not seem practical lead to a vision to build a wall that looked like a natural basalt cliff face. This reduced the construction time and made for a more interesting and aesthetically appealing wall, and the costs were almost equivalent to the usual precast panels.
“Great care has been taken to make the shotcrete wall appear as natural as possible,” say the judges. “Including the incorporation of water drainage through ‘wall cracks’.”
Concrete seating commended
Momo Seating in Christchurch was commended for its temporary transit lounge at the Christchurch Bus Exchange for the Christchurch City Council (the contractor was Fulton Hogan).
The challenge was to design a safe and robust lounge that was sufficiently enticing to move commuters away from the crowded bus stops on the footpath, and the seating was critical to its success.
“Although in a transit lounge of the Christchurch Bus exchange, these seats are suited for outdoor situations,” say the judges.
“They are made of painted, light-weight, pumice aggregate concrete and are attractive, playful, robust and surprising. They are heated by embedded electrical wiring.”
Contractor Vol.33 No.10 November 2009
All articles on this website are copyright to Contrafed Publishing Co. Ltd.