开口和闭口截面薄壁梁约束扭转效应对比分析OA

To compare the constrained torsional effect of thin-walled beams with open and closed sections,practical formulas for the constrained torsional geometric properties of open-section beams were derived based on the constrained torsional theory of thin-walled bars.The initial parametric solutions to the constrained torsional generalized internal force and displacement of simply supported and cantilever beams with open and closed sections were obtained.A thin-walled box girder was chosen as a numerical example and the corresponding open section beam was selected by setting fictitious cut at the center of bottom plate.The generalized internal force,displacement and stress for constrained torsion of two types of thin-walled beams were compared and analyzed in detail.The results show that the principal sector moment of inertia of the open section is about 19 times that of the closed section.The mid-span torsional angle of the simply supported beam with open section is about 4 times that of the beam with closed section.The generalized internal force(absolute value)of the thin-walled beam with open section is significantly greater than that of the beam with closed section.The mid-span bimoment and the warping torque of the simply supported beam with open section is about 27 times and 3 times respectively that of the closed-section beam.The warping stress of the open-section beam is significantly larger than that of the closed-section.