波形钢腹板箱梁的约束扭转剪应力分析

基于周边不变形理论,结合闭口薄壁杆件约束扭转的计算分析,研究了波形钢腹板箱梁在约束扭转时混凝土悬臂板上扭转剪应力的分布,并进行了计算.通过对悬臂板在约束扭转中剪力流计算公式的推导,进一步阐述了其自由扭转剪应力及翘曲扭转剪应力的分布,指出了相关文献在这部分计算中存在的问题.通过一个简支波形钢腹板组合箱梁算例,将该文方法计算结果与ANSYS有限元计算结果进行比较.结果表明:在波形钢腹板箱梁截面中,主要由波形钢腹板承受扭转剪应力,其次是混凝土底板,底板剪应力最大值发生在底板中心处,其数值近似等于腹板剪应力的一半,而混凝土顶板和悬臂部分的扭转剪应力很小;该文计算的扭转剪应力结果在总体上符合有限元得到的扭转剪应力分布规律,在悬臂自由端为0,随着离开悬臂自由端距离的增大,扭转剪应力逐渐增大并达到峰值.

Analysis on Restrained Torsional Shear Stresses of Box Girders With Corrugated Steel Webs

Based on the theory of circumferential non-deformation,and combined with the calculation and analysis on constrained torsion of closed thin-wall members,the distribution and calculation of torsional shear stresses were addressed for composite box girders with corrugated steel webs.The distributions of free torsional shear stresses and warping torsional shear stresses were further demonstrated through deduction of the formula for calculating the shear flow of cantilever plates in restrained torsion.The relevant shortcomings in calculating shear stresses by existing references were pointed out.A simply supported composite box girder with corrugated steel webs was taken as an example to compare the analytical results with those from the ANSYS finite element method.The results show that,in the sections of box girders with corrugated steel webs,the torsional shear stresses are mainly undertaken by corrugated steel webs,then by concrete bottom plates.The maximum shear stress in the bottom plate occurs at its center and is almost half that in the webs.The torsional shear stresses in the top concrete plate and the cantilever plate are very small.The calculated results of torsional shear stresses are consistent with those with the finite element method on the whole.The shear stress is zero at the free tip of the cantilever plate and gradually increases and reaches the peak value with the distance away from the tip end.