双向张弦梁找形的有限元法

根据双向张弦梁上弦压力和下弦拉力在节点产生的竖向分力与撑杆高度之间的关系推导了单元刚度矩阵,根据外荷载与上弦和下弦在节点产生的竖向分力相等的原则建立了以撑杆高度为未知数的双向张弦梁找形的线性有限元列式并编制了有限元程序,给出了张弦梁计算时下弦拉索初应变确定方法和张拉控制方法;通过对平屋顶和曲面屋顶双向张弦梁2个算例找形计算和受力分析验证了找形方法的正确性以及撑杆高度与屋面形状的无关性,本文给出的计算方法将撑杆高度作为未知量,考虑了上弦为曲面时拱的作用,计算方便、结果准确.

The FEM of form-finding of bi-directional string structure

The element stiffness matrix is deduced in the paper based on the relationship of the nodal vertical forces of up beams under axial pressure and down string-net under tensions to the heights of stay bars.The FEM to calculate the heights of stay bars is provided according to the principle of the external loads equaling to the nodal forces of up beams and the down strings,and the FEM program is written.The initial strains of the down strings used to calculate the bi-directional string structure and the tensio...