| This study presents a fatigue life evaluation of two steel-girder bridges along I-95 in Delaware. Both bridges are three-span simply-supported with composite deck construction. The evaluation methods used are based on NCHRP Report 299. Truck traffic is estimated from 2004 traffic summary data recorded by officials at the Delaware Department of Transportation. The standard 54-kip effective fatigue truck is used to represent the truck weight spectrum experienced by the bridges over their lives. Effective stress ranges are computed using basic methods of structural analysis including: influence line method, AASHTO lateral distribution factors, and average bending stress computation.; Both bridges, Br. 708 and Br. 746, were determined to have infinite fatigue life at their midspan locations. Also, Br. 746 possesses sufficient fatigue life at the termination locations of its bottom cover plate. However, Br. 708 does not have sufficient remaining fatigue life at the termination locations of its bottom cover plate. |
