A finite element modelling to investigate the mitigation of blast effects on reinforced concrete panel using foam cladding

Abstract

Protection of critical infrastructure against bomb attacks due to the rising threat of terrorism requires more attention. An effective solution to mitigate blast effects on infrastructure is to protect them with cellular foam material cladding. This paper investigates the capabilities of metallic foam cladding, which can absorb a significantly high blast energy being a cellular solid, in protecting critical reinforced concrete slabs against blast loadings. A coupled cladding structure interaction model based on the finite element technique has been developed to quantify the interaction between the cladding and the reinforced concrete (RC) slab subjected to blast loads. As the RC slab is supported at its two opposite edges and other edges are free in the present investigation, the slab is idealised as a beam in the proposed model where the small localised regions subjected to high moments are referred to as hinged regions which are connected with the large remaining parts of the structure referred to as non-hinge regions. The foam cladding layer over the RC slab is modelled as a lumped mass spring system which considers deformation of the foam layer in the loading direction. The hinge regions of the beam are simulated with interface elements having rotational stiffness which is obtained from a moment rotation model. The foam is modelled by an array of lumped masses over each beam element node connected by a number of inelastic extensional springs in the loading direction which help to model the progressive densification of the foam layer. Meanwhile a series of blast tests have been carried out by the DSTO (Defence Science and Technology Organisation, Australia) at their blast testing site at Port Wakefield, South Australia to investigate the effectiveness of the foam protected RC slabs against blast loads. The data recorded from the blast tests have also been used for the validation of the coupled cladding structure interaction model. © 2012 Elsevier Ltd. All rights reserved.