Experimental Study on Fatigue Performance of Steel-Concrete Composite Girders

Besides the static load, the fatigue load caused by vehicles always exists in the bridge structures. This type of loading may cause failure even when the nominal peak loads are less than the ultimate capacity of the structure. In this paper, an experimental work, consists of two specimens, was introduced to study the fatigue behavior of shear connectors and steel-concrete composite beams. The fatigue tests were conducted under a four-point bending test with two different stress ranges in a constant amplitude. The testing measurements during the fatigue test included deflection, strain in the shear connectors, and slippage between the concrete flange and the steel beam. After completion of the fatigue tests, it was obvious that providing top and bottom longitudinal reinforcement as well as enough transverse reinforcement in the concrete flange can provide adequate confinement to concrete to limit fatigue cracks in the concrete flange. In addition, a growth in the cyclic deflection limits was obtained by increasing the number of cycles due to the damage region that developed in the concrete flange by the shear studs and caused a loss of stiffness in the shear connection.