Factors Influencing Blast Attenuation on Walls With Foamed Concrete Boards

Abstract

As a FEA method is used to simulate blast attenuation with a foamed concrete board (FCB), effects of different factors on simulation results are studied. These factors include different boundary conditions, FCB thicknesses, FCB densities, and element sizes. Understanding the effects of these factors are very important prior to practically using FCB for the purpose of the blast attenuation in a structure design. The effectiveness of the blast attenuation is measured by the reduction of peak pressure acting on a rigid wall (RW) that is immediately behind and adhered to FCB. The simulation results indicate that the pressure history on RW and the internal stress of FCB between a full model and its quarter one are about the same. Differences on the RW pressures between nonreflecting and free boundaries are relatively significant for the small size of FCB. The increase of density and thickness of FCB can result in a further reduction on the blast pressure if the existence of FCB can indeed reduce the peak pressure. Otherwise, the increase of the density and thickness may not result in a final reduction on the peak pressure. It seems that the pressure reduction by increasing the thickness of FCB is more efficient than by increasing its density. Nevertheless the combination of density and thickness increases should maximize the effectiveness of the blast attenuation. The size of FEA elements does affect the value of the peak pressure on RW. As the element size decreases, the peak pressure tends to change in value and delay in time. According to the trend of the peak pressure with varying the element size, a proper size for a practical application should be determined based on the following rule that besides the consideration of better accuracy on the simulation results, the element size that gives relatively higher peak pressure, or is considered as consistently conservative in a design, should be recommended. Finally, based on the findings, a design procedure for the blast attenuation is proposed.