Shear Strength of Concrete-Encased Composite Structural Members

Abstract

This study investigates the shear strength of composite steel and concrete members in which the steel shape is fully encased in concrete. Two types of shear failure--diagonal shear and shear bond--are examined. By gaining an understanding of these failure modes, a new approach is proposed to predict shear capacities of composite members. Major parameters studied include steel flange width, shear reinforcement, concrete strength, and applied axial load. For evaluation of accuracy, a verification analysis is made by comparing shear capacities predicted by the proposed approach with previous test results. The shear capacities predicted by the proposed approach are also compared with those obtained by U.S. and Japanese provisions. Results of the analysis and comparison show that the proposed approach yields satisfactory prediction of shear strength, providing a rational explanation on the mechanism of shear bond failure. A new term, the critical steel flange ratio, is introduced to distinguish the shear bond failure from the conventional diagonal shear failure.