A Novel Model for Shear Strength Prediction of a Steel–UHPC Composite Structure Considering Interface Friction

Abstract

Existing studies have shown that the interface friction force positively affects and improves the shear behavior at the stud-connected steel–ultrahigh performance concrete (UHPC) interface. However, the effects of the interface friction force have not been well understood and quantified yet. The present study proposes a novel model to quantify the interface friction force and count it in the shear strength prediction for stud-connected steel–UHPC interfaces based on the compression-dispersion model and elastic foundation beam theory. The proposed formula is simple but with clear physical meaning, which has been verified with high accuracy. The proposed model can also be used to identify the yielding state of concrete in front of the stud and predict the interface friction during the whole static loading process, which improves the accuracy of shear strength prediction for steel–UHPC interfaces and reveals the influence of different parameters. For the steel–UHPC interface with UHPC strength greater than 120 MPa, the UHPC in front of stud is hard to yield and the percentage of friction force remains almost constant at 10%–14% during the whole static loading process. The positive effects of friction force on the shear strength of the steel–concrete interface is negligible for the cases with concrete strength less than 60 MPa.