钢筋混凝土U形薄壁梁弯-剪-扭复合受力性能试验研究

U-shaped thin-walled concrete girders are widely applied in urban rail transit projects, and they are usually subjected to the combined actions of bending, shear and torsion. In this paper, a large U-shaped thin-walled reinforced concrete girder specimen was tested under combined bending, shear and torsion to study its mechanical behavior, such as the crack pattern, the distribution of reinforcement strains and the failure mode,etc. The test results show an obvious spatial stress distribution. Not only cracks and reinforcement strains are distributed differently on the two webs, but also diagonal cracks and stirrup strains are distributed differently on the internal and external surfaces of a web. At support and mid-span sections, the distribution of longitudinal bars strains along the section height is in coincidence with the plane section assumption, and the longitudinal bars strains are distributed basically linearly along the girder span. Finally, ductile flexural failure dominated by bending moment and warping moment occurs only on the loaded side web, while the other web is under relatively low stress condition.