Simplified analysis of foam cladding protected reinforced concrete slabs against blast loadings

Abstract

Protection of infrastructure against blast loading has been receiving more attention in recent years due to occasional engineering explosion accidents, e.g., chemical plant explosion, and intentional man-made explosions, e.g., rising terrorist attacks. An effective solution to mitigate blast effects on these buildings is to protect them with sacrificial foam claddings for absorption of blast energy. However, little research has been conducted to analyze the effectiveness of metallic foam protected reinforced concrete (RC) structural members under airblast loads. This paper is to develop a numerical model to analyze the mitigation of blast effects on foam cladding protected RC members with consideration of interaction of blast load, foam layer and protected structural member. This numerical model is a simplified SDOF system where the deformability of the RC flexural member is considered in the form of the supporting spring. The stiffness of the spring K is estimated from the resistance deflection function of the RC member which is derived from combined moment curvature and moment rotation models. Material testing was conducted on aluminum foam specimens to obtain the stress stain curve which was idealised as a rigid-perfectly plastic-locking model. The resistance deflection curve of the RC slab and the idealised rigid-perfectly plastic-locking model for foam specimen were incorporated into the coupled SDOF interaction model for dynamic analysis. A field blast testing on foam protected RC slab was conducted and the accuracy of the coupled SDOF interaction model was validated by experimental data from the blast testing of the foam protected RC slab.