Fatigue behavior of full-shear-connection steel–concrete composite continuous beams under high-cycle loading

Abstract

Under cyclic loading, the mechanical performances of steel–concrete composite continuous beams (SCCCBs) and steel–concrete composite simply supported beams are different. The development of SCCCBs is hindered by the still unclear fatigue performances of SCCCBs. To study the fatigue failure characteristics of SCCCBs, the scaled full-shear-connection test beams were designed based on an original bridge. Generally, the test results showed that the stress amplitude affected the fatigue performance and fatigue life of an SCCCB. The fatigue failure of the full-shear-connection SCCCBs was controlled by the steel beams. The displacement, relative slip, bending stiffness, and bending moment all degraded in three stages with the increase in the number of loading cycles. In addition, the numerical simulations and parametric analysis with the rain-flow counting method and the linear cumulative damage criterion were carried out to analyze the fatigue behavior of SCCCBs. The validity of the numerical model was verified with experimental results. The influence of the steel nominal strength, span–height ratio, and load amplitude on the bending moment redistribution coefficient was further analyzed via the established numerical model. Compared with the stress amplitude, the nominal yield strength of steel and the span–height ratio had more significant effects on the redistribution of the SCCCB bending moment. Moreover, upon approaching fatigue failure, the redistribution coefficient of the section bending moment changed sharply, which is one of the key issues that should be considered in the fatigue performance study of SCCCBs.