Dynamic behavior and retrofitting of RC frame building under vehicular bomb explosion

Abstract

Although the terrorist explosion attacks on critical buildings caused by the Vehicle-Borne Improvised Explosive Device (VBIED) are low-probability events, the blast-induced progressive collapse of buildings generally lead to the catastrophic consequences of the events. Through the high-fidelity hybrid finite element (FE) model and numerical simulations, this work aims to get a deep insight into the progressive collapse behavior of high-rise reinforced concrete (RC) frame buildings under blast loadings induced by VBIED, as well as the feasibility of two blast-resistant external retrofitting measures, i.e., fiber reinforced polymer (FRP) and steel plate (SP). Firstly, the applicability of the hybrid FE modelling approach, element types and size, material models and parameters, as well as numerical algorithms, i.e., multi-material Arbitrary Lagrangian-Eulerian (MM-ALE) and Fluid-Structure Interaction (FSI), are fully validated by comparing with the explosion tests on 1/4-scale bare and prototype FRP/SP-retrofitted RC frame structures, respectively. Then, a twelve-story RC frame building is designed following the Chinese regulations, and the corresponding hybrid FE model is established. The failure modes and progressive collapse process of building under the explosions of cargo vans bomb (equivalent TNT of 1814 kg) specified by Federal Emergency Management Agency are numerically examined. Furthermore, the effectiveness of FRP/SP-retrofitted frame columns is assessed quantitatively. It derives that, the SP-retrofitted building is not collapsed for both the scaled distance of 1.0 and 0.55 m/kg^1/3; by retrofitting FRP warps, the collapse of entire buildings can be prevented with the scaled distance of 1.0 m/kg^1/3, while the progressive collapse of the retrofitted building occurs with a scaled distance of 0.55 m/kg^1/3. The present work could provide helpful references for the blast-resistant evaluation, design and retrofitting of the as- and newly-built RC building structures.