Residual axial capacity of seismically designed RC bridge pier after near-range explosion of vehicle bombs

Abstract

The terrorist bombing attacks on public transportation infrastructures, e.g., bridges, were increasing dramatically. Bridge pier damaged under the explosion will lose a portion of axial bearing capacity and may induce the partial and complete collapse of the whole bridge. This paper aims to numerically study the dynamic behaviors and post-blast axial capacity of the seismically designed RC bridge piers subjected to near-range blast loading of vehicle bombs. Firstly, by adopting the multi-material Arbitrary-Lagrangian-Eulerian algorithm, Fluid-Structure Interaction method, and erosion algorithm in LS-DYNA, a reliable and predictive finite element analysis (FEA) approach is established. Based on the existing three series of tests, the FEA approach is comprehensively verified by comparisons of blast overpressure, column deflection, spalling range of concrete cover, and residual axial bearing capacity. Secondly, the explosion scenarios of vehicle bombs on bridge piers are designed, in which the prototype bridge piers for three various earthquake intensity levels (EI7-EI9) are detailed according to the Chinese specification JTGT 2231-01-2020, and the compact and non-compact sedan bombs are concerned according to the requirements of FEMA-428, respectively. Then, the blast resistance of the above three seismically designed bridge piers under two typical vehicle bombs are evaluated based on the residual axial bearing capacity, and the influences of seismic detailing are further assessed quantitatively. Finally, a low-complexity engineering design approach is recommended based upon the seismic design and detailing provisions. The present work can provide helpful references for the damage assessment, blast-resistant design and further strengthening of RC bridge piers against the potential close-in explosions of vehicular bombs.