A Probabilistic Model for the Estimation of Shear Capacity of Bridge Piers Subjected to Dynamic Loading

The collision of vehicles has been identified as one of the most probable causes of bridge failure [Wardhana and Hadipriono 2003]. Accidental collisions of vehicles with key components of bridges, such as piers, might lead to severe consequences. In particular, piers are most vulnerable to collisions from high speed heavy vehicles. Recent design guidelines have provisions to design for equivalent static loads (ESL), but the loads are sometimes underestimated [El-Tawil et al. 2005]. Furthermore, recent design guidelines and provisions for collision of vehicles with bridges do not take into account the uncertainty associated with the collision event [Staples 2007]. Key issues such as the failure modes, the actual dynamic demand on the bridge due to vehicle collision, the bridge capacity to sustain a vehicle collision, and the interaction between vehicle and bridge are not addressed in the current design provisions. This paper develops probabilistic dynamic shear capacity (DSC) models for the bridges subjected to vehicle collision. The current probabilistic models for the shear capacity of bridge piers do not take into account the effect of rate of loading [Choe et al. 2007]. The proposed model accurately predicts the shear capacity of the pier subjected to dynamic loading. The probabilistic DSC model accounts for the uncertainties in the material and geometric property of the pier. The model is assessed using data from detailed Finite Element (FE) analyses. The FE model takes into account the rate of loading, different modes of failure and realistic support conditions. The analyses also account for the variability in loading, the material properties, and stiffness properties of the bridge. The FE simulations also provide valuable information to assess the typical failure mode(s) of bridges due to collision. The developed probabilistic DSC model can be used for a reliability-based design of bridge. It can also be used to easily design or estimate the adequacy of a bridge to sustain a collision event.