开口薄壁杆的板件面内拉弯综合抗力体系

摘要

In order to simplify the analyses of thin-walled open-profile bars,a thin-walled bar was split into two parts which were dominated by in-plane and out-plane loading effects respectively.The in-plane loading effects were focused.On the basis of appropriate simplified stress and strain conditions,each plate was analyzed and the results were integrated into vectors,resulting in the slabs' in-plane tension-bending resistance system of thin-walled open-profile bars,which reflects their axial stretch/compression,bending and warping properties.And then the deformation equation and the stiffness equation were set up.Because longitudinal interaction forces between plates were introduced in the definition of the plates' in-plane bending moments,the deduction and conclusions here were consistent in form with those in bending theory.Principal axes' directions,shear center's coordinates,principal inertia moments and sectorial inertia moment of thin-walled open sections can be deduced by the slabs-disassembled method proposed here.Lateral deformed bars' analysis based on those sectional parameters in classical theory is proved to be inefficient,where additional "rigid contour hypothesis" has to be introduced.%针对薄壁杆件力学分析较为复杂的问题,讨论了一种把开口薄壁杆的分析拆分为2个较简单部分的方法.针对薄壁中面内荷载效应的分析问题,首先在适当简化基本应力应变条件的基础上,按平面应力问题分析单肢板件面内荷载效应,然后对其进行向量综合,得到反映开口薄壁杆轴向伸缩、弯曲及翘曲性质的“板件面内拉弯综合抗力体系”及其变形方程；探讨了刚度方程的建立及其计算特点,并与经典理论进行对比.分析表明,在板件面内弯矩定义中引入板件间纵向相互作用力,可简化该体系分析过程和结论,使之具备与平面弯曲问题一致的形式.作为应用举例,推导了求解薄壁截面主轴方向、主轴惯性矩、弯心坐标、主扇性惯性矩的线性方程组,剖析了经典理论中这些截面几何特性对于计算的意义及其效率.