Construction materials that flex during a strong earthquake and then return to their original shape will be incorporated into a new bridge ramp on a downtown Seattle, Wash., highway.

Although modern bridges are designed to avoid collapsing during an earthquake, the technology takes the concept a step further. In earthquake lab tests carried out at the University of Nevada, Reno, bridge columns built using memory-retaining nickel/titanium rods and a flexible concrete composite returned to their original shape after a tremor of 7.5 magnitude.

The columns are built to flex and remain standing and usable. Image source: University of Nevada, Reno.The columns are built to flex and remain standing and usable. Image source: University of Nevada, Reno."We've tested new materials—memory-retaining metal rods and flexible concrete composites—in a number of bridge model studies in our large-scale shake table lab," says Saiid Saiidi, civil engineering professor. "Using these materials substantially reduces damage and allows the bridge to remain open even after a strong earthquake."

In an experiment featured in this video, one of Saiidi's bridges moved more than six inches off center at the base and returned to its original position, as designed, upright and stable. Using computer-controlled hydraulics, the earthquake engineering lab then increased the intensity of the recorded earthquake—to 250% of the design parameters—and still achieved what were reported to be excellent results.

The Seattle road project with the innovative columns is scheduled for completion in spring 2017.

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