Bridges, Tunnels and other Transportation Structures
External post-tensioning by means of high‐strength steel cables can be used to effectively increase the ultimate capacity of steel‐concrete composite beams. This paper presents static and fatigue tests on four steel-concrete composite specimens to evaluate the effect of externally post-tensioned tendons on the ultimate strength and fatigue behavior of composite beams. Fatigue tests were conducted to a million cycles under a four-point bending load. In addition, static tests to failure were performed on fatigued specimens to evaluate the residual strength of the strengthened specimens. A numerical model was developed to predict the fatigue response of the strengthened beams utilizing the fatigue damage in the concrete flanges. The accuracy of the developed numerical model is validated using the test data. The external post-tensioning significantly decreased the strains in the shear connector, in the concrete flange, and in the steel beam at all stages of loading. However, the concrete flanges experienced additional longitudinal fatigue cracks in comparison to the reference specimens.