Failure predictions for steel-UHPC-steel sandwich beams under three-point bending

In developing a steel-ultra-high performance concrete (UHPC)-steel sandwich structure (SUSSS) for some emerging applications, attention inevitably falls on the failure of the structure. Some typical failure modes have been summarized based on the experimental observations and numerical results. But the prediction of the failure mode is still a challenge. In the present paper, the failure of SUSSSs under three-point bending is investigated theoretically and numerically. A theoretical model is developed to predict the critical failure load of each failure mode on considering the tension-compression asymmetry of UHPC, and a failure mechanism map is constructed to predict the failure mode. The theoretical predictions are validated by the present numerical results as well as the previous experimental results. Based on the theoretical model, the effects of some geometrical and material parameters on the failure modes are discussed. It is demonstrated that the geometries of the SUSSS and the tensile strength of the UHPC core have remarkable effects on the failure modes of the structure. The present work provides a valid method to predict the failure modes of the SUSSSs.