Impact resistance of non composite axially restrained steel-concrete-steel sandwich panels

Steel-concrete-steel (SCS) sandwich panels are an effective means for protecting critical infrastructure facilities and personnel from the effects of blast and impact loading. This paper presents experimental results for axially-restrained non-composite SCS sandwich panels subjected to impact loads generated using a drop-hammer testing facility. The objectives of this experimental programme are to investigate the behaviour of axially-restrained non-composite SCS panels under large dynamic deformations and to study the effect of utilising reinforced concrete core. The sandwich panels consist of two mild steel faceplates connected together by two mild steel end plates and a concrete core sandwiched between them without using mechanical shear connectors. Three panel designs are experimentally investigated: (1) SCS panel with unreinforced concrete core, (2) SCS panel with nominally reinforced concrete core, and (3) SCS panel with heavily reinforced concrete core. The panels have specially designed keyed connections to restrain the axial movement, thus enabling development of the tensile membrane action in the panels under large deformations. It is found that while the flexural resistance of SCS panels increases with the increased amount of reinforcement in the concrete core, the strain energy absorbed by the panels remains nearly constant. It is also demonstrated that non-composite SCS panels with axial restraints can provide very high resistance to impact and blast loads through the mechanism of tensile membrane action at large deformations.