Evaluation of critical damage location of contact blast on conventionally reinforced one-way square concrete slab applying CEL-FEM blast modeling technique

Abstract

Nowadays, accidental explosions in residential and factory buildings are common owing to poor maintenance and mishandling of fuel gas and chemical explosive appliances leading to grievous injuries and infrastructure damages. Contact blast on slabs using explosives is noticed as a simpler act of subversion as compared to other components of the building and is more damaging than a close-in blast. In general, damage caused by contact blast is localized in the form of concrete cratering, scabbing, and rupture of the reinforcement. A recently published state-of-the-art review on the performance of reinforced concrete (RC) slabs under contact and close-in explosion loading scenario by the authors (Anas et al., 2021b) reveals the common perception for the location of contact blast to cause maximum damage is the centroid of the slab. It develops a curiosity with sufficient interest to investigate the effect of the location of contact explosive charge on the damage response of the slab. Several numerical techniques such as empirical, ConWEP (semi-empirical), Smooth Particle Hydrodynamics (mesh-free method), and Coupled-Eulerian-Lagrangian (CEL) are in use for simulation of blast loading on structures. Current literature reveals that the CEL is the most advanced and realistic blast modeling technique. This study applies Coupled-Eulerian–Lagrangian (CEL) formulation with finite element method (FEM) using the dynamic computer code ABAQUS/Explicit-v.6.15 to investigate the performance of singly reinforced one-way spanning concrete slab subjected to concentric contact blast loading. The numerical model is validated with the experiment results in the open literature. The validated model is then employed to investigate whether or not the maximum damage is really caused by the central location of the contact blast. For this purpose, one-quarter of the slab with nine symmetrical points (or locations) of contact blast of explosive charge, which reflect the coverage of the entire slab, in contact with the top face of the slab is considered in the study. Two constitutive material models, Concrete Damage Plasticity and Johnson–Cook, with strain rate effects are used to simulate the non-linear behavior of the concrete and steel, respectively. The results reveal that the most critical location of maximum damage to the slab is along the line of symmetry parallel to the supports at an eccentricity of B/4 from the centroid of the slab, where “B” is the width of the one-way slab.