Residual Flexural Capacity of Composite Beams with Corroded Studs after Fatigue

Steel–concrete composite beam bridges are subjected to vehicle fatigue loading and environmental corrosion during operation, which results in structural performance degradation and threatens the safety and durability of bridge structures. The purpose of this study is to provide an understanding into the residual flexural capacity of composite beams with different degrees of stud corrosion under fatigue. Five test beams are designed and fabricated: one test beam for static testing, one for fatigue testing, and three for corrosion and fatigue tests. Changes in the failure mode, residual flexural capacity, and relative slip are analyzed after different fatigue loading cycles of these composite beams at different stud corrosion rates. Based on fatigue residual strength theory and the corrosion hulling effect, the damage degree and residual strength of concrete, steel beams, and studs are obtained and a model for calculating the residual flexural capacity of these beams is established. The results show that the combined effect of stud corrosion and beam fatigue on the overall performance of a composite beam is significant and that the residual flexural capacity of the test beam with 9.1% stud corrosion rate decreases by 15% after one million fatigue loading cycles. After one million fatigue loads, the damage mode of the beams evolves from stud shearing to concrete crushing with higher stud corrosion rates, and a few mechanical indicators show a nonlinear degradation. The calculation values obtained using the residual flexural capacity model proposed herein agree well with the experimental results.