Cost Savings of Implementing Site-Specific Ground Motion Response Analysis in the Design of Short-Period Mississippi Embayment Bridges

Deep dynamic site characterization and a site-specific ground motion response analysis (SSGMRA) were conducted for a bridge site in Monette, Arkansas. The SSGMRA indicated the design acceleration response spectrum determined using the American Association of State Highway and Transportation Officials (AASHTO) general seismic procedure could be reduced by one third for the short-period range due to attenuation of the short-period ground motions. The steel girder pile-bent bridge, originally designed using the AASHTO general seismic design procedure, was redesigned using the updated seismic demands estimated from SSGMRA. A cost-savings analysis was then conducted to determine the potential savings associated with conducting the SSGMRA. By designing based on the results of the SSGMRA, a potential gross savings of $205,000, or 7% of the original bridge construction cost, could be achieved for the study bridge. Items that contributed most to the cost savings were the pile and embankment construction.