Impact responses of the steel-PU foam-concrete-tube multilayer energy absorbing panel: Numerical and analytical studies

The enhancement of structural protection can be achieved by using energy absorbing structures as sacrificial layers. In this study, a new steel-PU foam-concrete-tube multilayer energy absorbing panel (SFCTMEAP) is developed to improve the impact resistance of buildings and infrastructures, and its behaviour under impact loading is numerically and analytically studied. A Finite Element (FE) model is established using LS-DYNA to further study the behaviours of SFCTMEAP, and its results (including the failure mode, displacement-time and impact force-time curves) agree well with the test data. The SFCTMEAP presents a deformation mode of local indentation of the front energy absorbing layer, flexure of the steel-concrete-steel panel and collapse of PU foam filled steel tubes (PUFSTs). The energy dissipations of variant components of the SFCTMEAP are obtained through the FE model and the PUFSTs is the main energy absorbing component. In addition, parametric studies are performed to obtain the influences of the impact location, initial momentum of impactor and thickness of PU foam panel on the response of SFCTMEAP. The results indicates that the specimen with larger impact eccentric distance dissipates less impact energy, and raising the initial momentum of the impactor is benefit to the energy dissipation by the PUFSTs. Moreover, an analytical model is developed to calculate the displacement history of SFCTMEAP under the impact loading. The displacement responses predicted by the analytical model are found to be in good agreement with the test results.