Experimental investigation of steel-concrete composite beams with different degrees of shear connection under monotonic and fatigue loads

Abstract

Steel-concrete composite beams have been extensively used in buildings and bridges in recent years to combine these two construction materials. The behavioral characteristics of steel-concrete composite beams are related to the degree of shear connection. In this article, eight steel-concrete composite beams were investigated to examine the effects of different degrees of shear connection on the static and fatigue performances of the beams. First, the ultimate capacity, ductility coefficient, failure modes, strain distribution at the midspan section, and relative slip distribution of the steel-concrete composite beams under monotonic loads were investigated with different shear connection degrees. The effect of the shear connection degree on the fatigue life, failure mode, and other mechanical properties under fatigue loading was studied. The results show that all mechanical properties of the steel-concrete composite beams under monotonic and fatigue loads decrease with a decrease in shear connection degree, and their failure modes change with the decreasing shear connection degree. Second, based on the experimental results, the fatigue life of composite beams was analyzed and predicted under different assumptions of failure modes according to EC4, AASHTO, and the Chinese code. The result shows that different failure modes should be considered according to different shear connection degrees in the fatigue design of composite beams. Finally, the issues on the difference between static and fatigue capacities with different shear connection degrees and the critical point of the failure mode were discussed.