Fluid-structure interactions for the air blast loading of elastomer-coated concrete

Abstract

The fluid-structure interaction (FSI) effect experienced by an elastomer-coated concrete slab subjected to blast loading in air is studied numerically. The aim is to establish whether a flexible coating alters blast-structure interactions and whether this can explain the apparent blast mitigating capability of this retrofit solution as reported in published experimental investigations. Numerical models for a typical concrete and spray-on elastomer coating are established and a Coupled Eulerian-Lagrangian (CEL) model is employed to predict the air blast response. A 1D FSI analysis suggests that the elastomer coating increases the peak compressive stress in the concrete during short timescale pressure wave interactions. But the effect on the total imparted momentum is small, across a range of target mass and blast intensity. However, due to momentum sharing, the impulse imparted to the concrete plate is reduced in the coated configuration. By extending the analysis into 2D, it is found that the displacement of a concrete slab is marginally reduced when coated on either the blastreceiving or non-blast-receiving face. Thus, it is postulated that the elastomer contributes a small, beneficial mechanical effect. Finally, the need for a fully coupled (CEL) approach to model the blast-structure interaction is interrogated. For a wide range of cases, the results suggest that using a purely Lagrangian approach, in which a pressure-time history is directly applied to the structure (thereby neglecting full representation of FSI effects), is sufficient to capture the deflection behaviour of coated concrete plates. However, it is shown that the significance of the error associated with this simplification depends on the blast intensity and slab geometry under consideration.While new buildings can be designed with higher threat levels in mind, existing structures 12 remain vulnerable if the threat level changes. Retrofitting buildings and infrastructure for 13 enhanced blast resistance is one approach to solving this problem. One particular retrofit 14 solution that has gained attention in recent years is the use of a spray-on elastomer coat-15 ing. Early experiments on masonry structures yielded encouraging results regarding the 16 elastomer's ability to contain blast debris [2, 3]. Further work on elastomer application to 17 steel plates has suggested that it is also capable of significantly reducing peak deflections 18 due to dynamic loading [4][5][6]. However, there is some debate in the literature regarding the 19 optimum coating location i.e. whether it is more beneficial to coat the blast-receiving or 20 non-blast-receiving face. Indeed, some researchers have reported that the coating can have 21 detrimental effects if applied to the load-receiving face of a steel substrate [4, 5]. 22Comparatively little work has focused on spray-on elastomers applied to a concrete sub-23 strate, despite concrete representing a significant proportion of the aging, vulnerable infras-24 2 tructure in today's built environment that could ben...

Impact mitigating capabilities of a spray-on elastomer coating applied to concrete

“…Most studies to date have tended to focus on the mitigating capabilities of such coatings in response to blast pressure pulses. Promising results have been reported for coatings applied to masonry [1,2], steel [3,4] and reinforced concrete [5][6][7] substrates. However, relatively few investigations have been performed to assess the influence of an elastomer coating on the damage due to fragment impact.…”

Experimental and Numerical Investigation on the Impact Response of Elastomer-Coated Concrete

“…We choose a hyperelastic relationship, based on the Yeoh strain energy potential and strain rate effects are accounted for by incorporating viscoelasticity using a Prony series. More details are described in [7].…”

“…Concrete represents a significant proportion of today's ageing infrastructure and given its tendency to emit secondary fragmentation upon impact (due to cracking and spallation), it appears a suitable candidate for this protective solution. Previous work [4,7] has focused on assessing the elastomer's ability to protect RC from blast pressure pulse loading and it is found to be most effective in high blast intensity regimes when the concrete is severely damaged. Here, we turn our attention to its impact mitigating capabilities.…”

Numerical Analysis for Critical Structures Protection against Blast Loading Using Metallic Panels

“…Furthermore, Palta et al [31] investigated the dynamic responses of monolithic steel plates, multilayer steel plates, and hybrid plates constructed from steel and Kevlar layers against a blast load. Fallon et al [32] numerically studied the fluid-structure interaction effect on a coated concrete slab subjected to blast loading. Furthermore, the amount of explosives was determined by knowing the incident pressure peak value, while the negative pressure was determined from the pressure after decay [33].…”