Effects of Truck Impacts on Bridge Piers

According to Federal Highway Administration, impact by moving trucks is the 3rd leading cause of bridge failure or collapse in the country. Although current AASHTO LRFD Guide Specifications prescribe designing bridge piers by applying a 400 kips static load at a height of 4ft to improve their impact resistance, recent studies have shown that the dynamic forces because of truck impacts may be significantly higher than that recommended by the AASHTO Guide Specifications. In this paper, we present an extensive investigation on the impact of a three-span steel girder bridge with reinforced concrete piers by trucks running at different speeds through models of bridge and the truck in LS-DYNA, including a correlation between seismic and impact resistance of bridge piers. Results also present a comparison between static load prescribed by AASHTO Guide Specifications and dynamic impacts loads observed during numerical simulations. A performance based approach is proposed to design bridge piers against truck impacts.