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David Unwin / Things
The Whirokino trestle bridge between Foxton and Levin was being demolished on Tuesday.
Seismic research on the dismantled Whirokino Trestle Bridge at Foxton will give an idea of the strength of such structures to resist earthquakes.
The 90-year-old bridge on State Highway 1 south of Foxton was recently replaced by a new structure.
Dr. Lucas Hogan of the University of Auckland began examining the bridge two weeks ago and the demolition began on Monday.
Hogan said the out-of-service bridge created an unprecedented opportunity to do “real-life” tests of how a long bridge, spanning 1.1 kilometers, behaved in an earthquake.
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David Unwin / Things
The out of service bridge created an unprecedented opportunity to examine how structures were affected by earthquakes.
“We’ve done a lot of bridge testing in the lab, and this is a unique opportunity to test a real bridge and even lead to failure,” said Hogan.
It would provide engineers with information on how they could care for existing bridges and ensure that the structures are as strong as possible during an earthquake.
The investigation, funded by the Earthquake Commission and QuakeCoRE earthquake resistance research group, was carried out in cooperation with the New Zealand Transport Agency and had been ongoing for two years.
“A big focus will be on how the piles supporting the bridge behave in earthquake conditions. These types of batteries are used in about half of all bridges in New Zealand, and many internationally, making it a very practical science, “said Hogan.
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The view of the old Whirokino Bridge, on the right, and the new bridge over the Manawatū River and the Moutoa floodplain near Foxton.
He didn’t know how the bridge would withstand testing, but if there were problems with its structure, many other bridges in New Zealand could face similar difficulties.
Hogan said the tests included installing instruments on the bridge to find out how it moved.
Because seismic waves travel at a finite speed, one end of a bridge will start to shake before the other. On a long bridge, this can cause an arc saw effect.
“While many computer models have demonstrated this effect, there is very little physical evidence to prove it.”
The research runs for 10 weeks and includes removing sections for testing at the University of Auckland, as well as testing the piles on site to simulate earthquake stress by pushing and pulling in a controlled manner.
Supplied
The 90-year-old bridge on State Highway 1 south of Foxton was recently dismantled by the New Zealand Transportation Agency.
“This will tell us a lot about how these bridges behave after 90 years of service. Having the entire bridge means we can also try possible solutions to make the columns and stacks more robust, which could be used on any similar bridge if needed. “
Transportation agency senior project manager Andrew Thackwray said that with more than 4,500 bridges on New Zealand’s road networks, strong and secure bridges were vital to keeping the country moving.
“New Zealand engineers have created an excellent network of bridges that have proven to be extremely robust despite all the natural hazards we are exposed to in this country. This research will allow us to continue that proud tradition and build even stronger bridges. “
The agency was working with Brian Perry Civil and deconstruction experts from Jurgens Demolition to support the scientists conducting their research.
