Experimental and numerical investigations on impact response of reinforced concrete beams with a sandwich panel protective layer

This paper investigates the response of reinforced concrete beams protected by an aluminium foam sandwich panel under impact loadings. A series of impact tests were conducted on one reinforced concrete beam and five beams with a protective layer, focusing on their dynamic responses and failure patterns. Test parameters included the type of protective layers (unprotected, aluminium foam and sandwich panel) and impact energy. Test results showed that the aluminium foam and sandwich panel could effectively protect the reinforced concrete beam from severe damage under impact loadings and converted the failure pattern of beams from shear failure to flexure-shear failure. Compared with the unprotected beam, the beams with a protective layer exhibited a lower peak force and developed a smaller mid-span deformation. Besides, the protective effects of the aluminium foam and sandwich panel were found to be nearly the same. Moreover, the peak force, plateau force and deformation of the beams were increased with the increasing impact energy. A numerical model was developed to investigate the energy distribution of beams with a sandwich panel protective layer. Based on the validated model, the effects of longitudinal reinforcement ratio and shear-span ratio on the impact response of beams were further studied. It was found that the deformation of beams increased significantly with the increasing shear-span ratio, whereas an increase in the longitudinal reinforcement ratio led to a decreased deformation. This study provides an important reference for designing reinforced concrete beams with a sandwich panel protective layer to resist impact loads.