Investigation on the bearing capacity of weathering steel-concrete composite beams exposed to corrosion conditions

Weathering steels are frequently used in bridges nowadays due to the excellent corrosion resistance , which is a major factor for the service life. It is of interest to investigate the corrosion-bearing capacity of weathering steel-concrete composite beams since atmospheric corrosion could result in material properties degradation and structural damages. In this study, static load tests were firstly performed to reveal the material and structural performances of the weathering steel-concrete composite beam in chloride and sulfate corrosion conditions. Then, by integrating the test information of both weathering steel and reinforced concrete, a nonlinear finite element model was established to investigate the bearing capacity degradation and its time-varying law of weathering steel-concrete composite beam. The results demonstrated that, although the material properties of weathering steel-concrete composite beam deteriorated due to corrosion, the ductility and bearing capacity outperformed those of carbon steel-concrete composite beam in the same corrosion conditions. The yield load and deflection of the weathering steel-concrete composite beam decreased along with the corrosion time. Unlike the linear degradation process of carbon steel-concrete beam, its bearing capacity loss rate exhibited a slow initial rise, followed by a rapid increase after 60 days of accelerated corrosion due to the reduced strength and thinned thickness of weathering steel.