Researchers at University of British Columbia (UBC) Okanagan have determined smart memory alloys are a safer and more cost-effective alternative to steel reinforcement in earthquake-prone areas like the Lower Mainland in B.C. Memory alloys, which can be flexed without experiencing permanent damage, can maintain a bridge’s structural integrity and significantly reduce repair costs after a seismic event, finds the study.
For years, steel rebar reinforcements have been employed in the construction of structurally sound bridges. However, these structures are extremely rigid and can experience permanent damage after a seismic event.
Although seismic design guidelines in North America and Europe allow bridges to undergo deformations during an earthquake as long as they remain intact, the repair costs can be considerable.
“More than 100 steel reinforced concrete bridges had to be completely demolished and rebuilt after the Kobe earthquake in Japan in 1995, even though they were still standing,” says Shahria Alam, associate professor of engineering at UBC’s Okanagan campus.
As countries like Canada look to upgrade aging infrastructure, Alam says governments are eager to find safe and cost-effective options.
In an effort to build a “smarter” bridge, Alam and his former PhD student Muntasir Billah, a bridge engineer in Vancouver, designed five bridge piers reinforced with different alloy materials and then vigorously tested them under a variety of earthquake scenarios mimicking the seismic risks of the Lower mainland.
Using a combination of numerical models and computer simulations, the researchers were able to determine which alloys are most effective in maintaining the bridge’s integrity while reducing repair costs.
“All of the memory alloy bridges performed exceptionally well, but one alloy in particular, called ferrous polycrystalline, was a clear winner,” says Alam, who is one of the university’s researchers of the year. “It could represent a significant advance in the safety and financial viability of bridge construction in this region.”
Their latest findings have been published in the journal Engineering Structures. The research was funded through a Discovery Grant by the Natural Sciences and Engineering Research Council of Canada (NSERC).