Ultimate strength behaviour of S-UHPC-S and SCS sandwich beams under shear loads

The application of steel-concrete-steel (SCS) sandwich structures as containment buildings is proposed for the third-generation nuclear power plant AP1000. In this paper, ultra high-performance concrete (UHPC) is developed as the core material to improve structural behaviour. Static tests on two groups of SCS sandwich beams and two groups of steel-ultra high- performance concrete-steel (S-UHPC-S) sandwich beams were carried out to investigate the structural behaviours under three-point loading, with the research parameters consisting of the shear reinforcement ratio and core materials. Three failure modes are defined and the structural behaviours are analysed, considering the effects of the shear reinforcement ratio, shear studs and core materials on the specimens. Based on the test results, mechanical models are established to predict the shear bearing capacity of SCS sandwich beams, taking into consideration the effect of the contribution of the steel plates and the bond-slip action between the steel plates and concrete. Furthermore, a calculation method for predicting the ultimate strength of S-UHPC-S sandwich beams is presented, which takes into account the effects of steel fibres on specimens. The prediction accuracy is verified by means of comparison with the test data.