Over-height vehicle impact with bridge girders having different boundary conditions

The majority of bridges in the US were constructed using prestressed concrete systems. Collisions between over-height trucks and bridges are common accidents. Based on an unpublished survey carried out by the PI, approximately one such accident occurs weekly across the U. S. Limited research, however, carried out to investigate the performance of bridge girders subjected to impact loads. This proposal aims to investigate the performance of prestressed bridge girders subjected to vehicle collision. The research will complement an ongoing pooled-funded project carried out by the PI to investigate the same issue. This MATC-funded project focuses on the effect of the concrete deck on impact testing of prestressed girders. In particular, three prestress girders having different torsional constraints will be investigated. All girders will be laterally constrained at both ends. Furthermore, the first girder will not be constrained against any torsional rotation. The torsional rotation of the second girder will be constrained at both ends. The third specimen will consist of multiple prestressed girders connected using a rigid reinforced concrete deck. The three specimens will be subjected to impact loads that cause different levels of damage. The impact load will be imposed using a cart that slides on a rail. The tests will determine the effects of the torsional constraints on the damage level and impact forces.

This research aims to determine: 1) the impact force and damage of prestressed concrete girders, and 2) the effects of deck constraints on the damage of the impacted girders.

Over-height truck impact with bridge girder incidents occurred quite often in the U.S., causing different levels of damage to the impacted girders. Repair of such damaged girders is quite expensive, with an average repair cost of $0.5M (Fu et al. 2003). A limited number of experimental works were carried on prestressed concrete girders. However, this limited experimental work was carried out on isolated beams, i.e., concrete beams, without considering the effect of the concrete deck. The proposed experimental work will investigate the effect of the constraints imposed by the deck on concrete girders. This research will quantify the damage that occurs in bridge girders due to vehicle impact. In conjunction with the ongoing pooled-funded project, the outcome of this project will help structural engineers better understand the effects of vehicle impact on bridge girders and the residual strength of the damaged girders.

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