Bending response of steel-UHPC-steel sandwich composite beams

The construction of large-scale projects such as nuclear power plants, offshore platforms, and immersed tube tunnels has driven the development and application of steel-UHPC-steel sandwich composite structures (SUSSCSs). Due to the nonlinearity of the material, the complex geometry of the structure, and the dependence on the failure modes, it is still a challenge for existing theories to predict the mechanical response of steel-UHPC-steel sandwich composite beams (SUSSCBs) beyond elastic stage. In this paper, a theoretical model is proposed for predicting the entire bending response of SUSSCBs. The theoretically predicted force-displacement curves of the SUSSCBs are compared with the previous experimental measurements and the present numerical results, which are in good agreement. The results demonstrate that the bending response of SUSSCBs is dominated by the material properties and geometric parameters of the structure, such as span, tensile strength of UHPC and yield strength of steel plates. This research contributes to a deeper understanding of the mechanical behaviors of SUSSCBs under bending, and a basis for designing this kind of structures. © 2025 Institution of Structural Engineers