Impact Forces from Heavy-Vehicle Collisions with Bridge Piers

Guidance on how to design a bridge pier for heavy-vehicle impact is limited. AASHTO's Load and Resistance Factor Design Bridge Design Specifications cites a 400-kip design load but no detailed methodology to apply it. Furthermore, the magnitude was established on the basis of a limited set of data. This paper presents detailed analyses of bridge piers under heavy vehicular impacts, which were performed at the Texas A&M Transportation Institute. With the use of finite element analyses, the impact force was quantified with respect to pier diameter, vehicle type, total vehicular mass, and ballast type (i.e., rigid or deformable). In addition, a full-scale crash test was performed with an 80,000-lb tractor trailer, which hit an instrumented pier to quantify the impact force and its distribution. Analysis of the test and the simulation concluded that a 600-kip load was appropriate as the recommended design load for a bridge pier exposed to heavy-vehicle impacts. In addition, researchers at the Texas A&M Transportation Institute recommended application of the load 5 ft above ground and 0° to 15° from the pavement edge.