Unified Analytical Model for Predicting Internal Forces in a Bridge Column Subjected to Vehicular Collision

Numerical modeling for analyzing complex phenomena occurring under transient conditions is well established. Even then, simplifying a vehicular collision to an equivalent static load is prevalent in the structural design of a highway bridge. Use of algebraic expressions for determining the magnitude of the equivalent static load is preferred in practice, because the relative significance of various controlling parameters is automatically transparent. However, the equivalent static load approach has fundamental limitations, which are exemplified when dealing with changes to road traffic conditions requiring adjustments. The new analytical model introduced in this article is unique because it features the use of algebraic expressions founded on the theory of dynamics of structures for determining deflection and force demand resulting from a vehicular collision. The theoretical model, which is versatile and scale insensitive, has been verified by comparison against results from numerical simulations. The numerical model, in turn, has been verified experimentally. Application of the proposed model for predicting internal forces in a bridge column is illustrated. Input to the model is an idealized forcing function of time representative of the collision of a heavy truck. The proposed model, although simple to use, is shown to accurately capture the predominant effects that the inertial resistance of the bridge deck has on the shear force and bending moment of the bridge column. This inertia phenomenon cannot be accounted for by any existing calibrated static force model. Further, the effects of the crumbling of the vehicle resulting in prolonged contact with the column can also be captured but are neglected in a static analysis.