Experimental and Analytical Study of Dynamic Behavior of Bridge Superstructures Subjected to Overheight Vehicle Collisions

The increasing occurrence of over-height vehicle collisions with bridges in the United States leads to concern about the damage due to lateral impact to bridge superstructures by over-height vehicles. However, this issue is not fully addressed in current bridge specifications. Previous researchers have conducted a number of small-scale tests to study the impact process. Also, finite element method (FEM) has largely been used to analyze the complicated collision mechanism.

A full-scale lateral impact testing facility was designed and built on a construction site in Knoxville, Tennessee, United States. An AASHTO Type-I prestressed concrete (PC) girder and a Hybrid Composite Beam (HCB) bridge were tested using this facility, which led to a realistic level of damage and mechanism analysis of bridge superstructures under lateral impact loading as described in this dissertation. The failure of the PC girder was first introduced by punching shear around the impact zone. With the penetration of the impactor, the damaged impact zone behaved as a “hinge” which moved upward due to the heavy weight of both overhangs. HCB bridge experienced no global failure but only local damages of the FRP shell around the impact zone. Impact energy was mostly absorbed through strain energy of the tension reinforcement and the low-density foam and dissipated through local damage of the FRP shell.

Commercial software ABAQUS/Explicit was used to develop FE model of the PC girder and the FE results were compared with the experimental results. Parametric study was also performed to evaluate the behavior of the PC girder under different impact conditions.