水平荷载作用下交错桁架结构的内力和侧移计算

本文通过对交错桁架结构在水平荷载作用下受力特点的分析,把结构中的楼板等效于与横向框架铰接的刚性链杆,建立了构件内力、层间侧移和楼层侧移计算的平面协同分析模型。通过对结构中柱子和竖向腹杆的受力分析,给出了交错桁架结构中柱子和竖向腹杆侧移刚度的力学计算模型和计算公式。根据水平荷载作用下桁架中远离空腹节间的弦杆弯矩较小的特点,假定桁架弦杆只在空腹节间和与其相邻的节间存在弯矩,给出了桁架侧移刚度的力学计算模型和计算公式。在楼板刚度无穷大假定的基础上,运用同一楼层水平侧移相等这一条件,提出了考虑柱子轴向变形影响的刚性链杆中轴力、构件内力、层间侧移和楼层侧移的计算方法。实例分析结果表明,本文方法简单实用,与ANSYS分析结果接近。

Calculation of internal forces and drift of staggered truss structure under lateral loads

Based on the analysis of the bearing characteristics of staggered truss structure under lateral loads,considering the floors in the staggered truss structure being equivalent to rigid bars hinged with transverse frames, a plane cooperative mechanical model for calculating internal force in member, relative drift between neighbouring storeys and total drift of storey was established. With the mechanical analysis of column and vertical web member in the staggered truss structure, a mechanical model and formula for calculating lateral stiffness of column and vertical web member were presented. According to the characteristics that the moments of chords in the panel away from the Vierendeel panel were small and the assumption that the moments of chords were only considered in the Vierendeel panel and those adjacent to it under lateral loads, a mechanical model and formula for calculating lateral stiffness of truss were put forward. On the basis of the assumption that the stiffness of floor was infinite and the lateral drift kept equal in a same story, a method for calculating axial force in the rigid bar, internal force in member, relative drift between neighbouring storeys and total drift of storey was suggested in which the deformation of column caused by axial force was considered. The calculation examples showed that the results obtained by the method developed in this paper were adjacent to the analysis results of ANSYS, and the method adopted in this paper was simple and practical.