Energy absorption performance of steel plate-polyurethane foam composite protective structures

In recent years, accidents of vehicles (or vessels) hitting bridge piers have occurred frequently, posing serious threats to the safety of the bridge structures, vehicles, and people. Due to their energy-absorbing effects, flexible protective structures have the potential to reduce the damage of both the bridges and vehicles. Therefore, it is of great significance to develop flexible protective structures with high performance of energy absorption. In this study, a new type of steel plate-polyurethane foam composite protective structure was proposed, in which the face panels and webs were made of flat and folded steel plates, respectively, and polyurethane foam was used as the filling material. Basic mechanical behavior of the composite protective structure was studied through static compression tests; and the influences of three key variables (i.e., web form, foam density and foam-filling pattern) on the energy absorption performance of the structures were focused. The results showed that the energy absorption (EA) and crushing force efficiency (CFE) of the folded-web specimens without foam filling were higher than the straight-web counterparts by 19.6 % and 74.2 % on average, respectively; and the EA and CFE of the folded-web specimens fully-filled with a foam density of 50 kg/m3 (100 kg/m3) were 30.6 % (33.8 %) and 124.7 % (116.6 %) higher on average than the straight-web counterparts, respectively. In addition, it was found that there was a positive composite effect between steel plates and polyurethane foam; but the polyurethane foam on the outside of the protective structure was prone to bending deformation, which weakened the energy absorption performance of the structure to a certain extent. In the future, the proposed composite protective structure can be further optimized to achieve better energy absorption performance, so as to provide a better solution for the impact protection of bridge piers or other structures.