Simplified Analysis of Foam Cladding Protected Reinforced Concrete Slabs against Blast Loadings

Abstract

A AB BS ST TR RA AC CT T 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.

Numerical Analysis of Metallic Foam Using Microstructure Model

“…The simulated strain in the elastic phase seems to be smaller in comparison with the predicted strain, while a much longer extended plastic plateau for metallic foam is obtained in the numerical simulation. Moreover, the simulated densification strain is approximately around 60% which matches well with the value for aluminum foam (Wu et al 2011). Figure 7, from which it is observed that the deformation firstly concentrates on the one or two layers of weakest region of specimen.…”

“…Recent research indicates that newly developed mobile and lightweight materials, such as metallic foams which have high capabilities to dissipate energy as they are cellular solids, are very attractive for use as cladding in applications for protection against external blasts (Wu et al 2010(Wu et al , 2011Sadot et al 2005). Newly developed lightweight materials such as honeycomb and aluminium foams exhibit special pore microstructures as shown in Figure 1 (Lu and Yu 2006) and have been widely used as good energy absorbing materials.…”

Numerical Analysis of Foam-Protected RC Members under Blast Loads

“…The numerical model used in the current research was based on field blast tests carried out by Zhu et al [23], whose blast testing data were previously used to validate a single degree of freedom model [24] and a simplified finite element model [25]. However, the accuracy of these models is relatively low.…”

Experimental Study of the Effectiveness of Sacrificial Cladding Using Polymeric Foams as Crushable Core with a Simply Supported Steel Beam

“…Considerable research has been conducted on the study of protective structures aiming at reducing the transmitted pressure to the main structure. Sacrificial cladding structures receive a lot of attention [1][2][3][4][5][6][7][8][9][10]. They consist of a crushable core between the main structure and a front plate.…”

“…However, these cores are characterized by a relatively high plateau stress (between 1 and 10 MPa [14]) to protect a given structure. Wu and Zhou [9] study the use of foam cladding to protect a simply supported reinforced concrete (RC) slab against blast loading. They use an adapted SDOF model supported by a full scale experiment to study the effectiveness of aluminium foam on RC slab.…”