Punching shear behavior of steel–concrete–steel sandwich composite plate under patch loads

• To experimentally study the ultimate strength behavior of a steel–concrete–steel sandwich plate under concentrated loading.
• To investigate influences of different parameters on ultimate resistances of a steel–concrete–steel sandwich plate.
• To develop design equations to predict the ultimate resistances of a steel–concrete–steel sandwich plate.

This paper studied the structural behaviors of steel–concrete–steel sandwich composite plates under patch loads. Ten SCS sandwich plates, adopting an ultra-lightweight cement composite (ULCC) and overlapped headed studs as the bonding measures at the steel–concrete interface, were simply supported and subjected to patch loads till failure. The investigated parameters included spacing of the connectors, strength of the ULCC core, thickness of the steel skin, volume fraction of the fiber, and depth of the cross section. Test results estimated the size of the punching cone and showed that load-defection behaviors of the SCS sandwich plate contained five stages. The influences of the different parameters have been discussed and analyzed. Analytical models have been developed to predict the ultimate resistances of the SCS sandwich plate under patch loads through modifying the code equations. These innovations and modifications included developing models to predict the tensile resistance of the connectors, incorporating the contribution of the top steel skin on the punching shear resistance, consideration of the tensile resistance of the connectors on the second peak resistance of the structure, and adopting a proper critical perimeter. The validations of the predictions against the test results showed that the code provisions overestimated ultimate resistances of the SCS sandwich plates and the developed analytical models offered reasonably good agreements. Design recommendations were finally given based on these validations and discussions.