Load Effect, Safety Assessment, and Traffic Strategy of Multigirder Bridges under Lateral Eccentric Customized Transport Vehicle

Customized transport vehicles (CTVs) are usually required to travel along the bridge centerline at low speed. However, emergency situations might occur on the bridge during the passing of a CTV and result in partial closure of the traffic lane. To investigate whether the CTV could pass over multigirder bridges in a manner of lateral eccentric load, five critical CTVs were extracted from long-term recorded data, and the dynamic simulation analysis of 360 different CTV load cases was accomplished. Bending bearing safety assessments of small-to-medium-span multigirder bridges under lateral eccentric CTV loads were conducted and the applicability of specified axle weight limits analyzed by using a load rating method, in which the partial factor of CTV load effect is optimized considering the balance between failure cost and benefit. The results show that when the lateral eccentric distance is not greater than 2.5 m, all safety indices are lower than 0.879 and the bending bearing capacities of multigirder bridges are deemed to meet safety requirements. The safety indices of bridges under fully loaded critical CTVs are lower than 0.977, and the specified CTV axle weight limits are applicable when the lateral eccentric distance reaches 2.5 m. To prevent the structure from entering the plastic stage, the lateral eccentric distances of C-IV and C-V, which denote the fourth and fifth vehicle type, are suggested to be less than 2.0 m when they pass over prestressed T-beam bridges.