Behavior and Design of Bridge Piers Subjected to Heavy Truck Collision

Heavy trucks, such as tractor-semitrailers weighing up to 360 kN, represent a serious collision hazard for unprotected bridge piers. Current specifications recommend designing a bridge pier vulnerable to vehicular impacts for a static force of 2,670 kN applied on the pier at a specified height. However, the impact load delivered by a heavy truck is dynamic and not applied at a single height during the crash process. High-fidelity computational simulation is used to gain insight into how force is delivered to a bridge pier during a crash. The impact force time histories generated during a collision are simplified into a series of triangular pulse functions applied at various heights. Key parameters defining the pulse models are truck weight, approach speed, and pier size. The values of these parameters are derived from numerical regression based on the simulation results. By comparing pier damage modes and deformation profiles, the proposed pulse model is demonstrated to be able to accurately represent the truck impact demands. We have proposed a capacity design philosophy to mitigate the effects of shear failure. We revealed that piers designed according to the proposed philosophy are less likely to fail in shear compared with regular piers. We asserted that together, the simple pulse model and proposed capacity design approach can serve as a basis for future performance-based design provisions for bridge piers subjected to heavy truck impact. © 2019 American Society of Civil Engineers.