Numerical Modeling and Performance Assessment of Bridge Column Strengthened by FRP and Polyurea under Combined Collision and Blast Loading

Abstract

Highway bridge piers could be underdesigned for a multihazardous condition involving vehicle collision and air blast based on the current design code. The piers are often positioned in such a fashion that it is neither possible nor economically feasible to place protective devices around them. This paper numerically investigated two potential strengthening techniques, the placement of a fiber-reinforced polymer (FRP) wrap and polyurea coating onto the column surface, to improve column resistance against the extreme demands from combined collision and blast loads. Finite-element models of isolated reinforced concrete (RC) columns with an FRP wrap and polyurea coating were developed using a commercial software, LS-DYNA. The modeling techniques were validated separately against impact and blast experimental results. Collisions were supplied from a medium-size F800 single-unit truck at various velocities, and air blasts of varying magnitude were represented using the arbitrary Lagrangian–Eulerian approach. Bare and strengthened column response to various collision and blast demands was compared to assess the effectiveness of strengthening. The results indicated that using the FRP wrap and polyurea coating on columns could effectively mitigate the effects of combined vehicle collision and air blast. The effectiveness of each scheme differed as a function of geometric and material properties and column demands. Parametric studies were then conducted to evaluate the influences of various design parameters on column performance and identify optimal strengthening schemes.