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Strengthening Bridges

South Dakota State University

Nadim Wehbe, director of the Jerome L. Lohr Structures Lab, said that testing has revealed that a new means of joining precast double-tee bridges can dramatically increase a bridge's lifetime.

The conventional means of joining the girders failed at 31,500 load cycles - about six years of average traffic.  An experimental lattice method design of joining double-tee girders showed no change in performance after 800,000 load cycles - more than 75 years of service.  Engineers estimated the new design costs only 3.5% more to install than the conventional method.  Wehbe joined Cara Hetland on Innovation Friday at South Dakota State University in Brookings.