In the code for design of steel structures, the effective length factor of the support and other web members of the steel trusses composed of double angle steel were taken as 1.0 and 0.8, respectively. However, the effective length factor of the support and other web members did not take into account factors such as the stiffness provided by non-adjacent members, the stiffness of the joint itself, and the influence of load changes in the code for design of steel structures. To consider the above influencing factors, a finite element model, based on the steel truss atlas, was established in Abaqus, the elastic restraint stiffness of the web member end was obtained through numerical analysis. The equation was established according to the restraints of the web member end, and the effective length factors of the web member were obtained by solving the equation with Matlab. The analysis found that the elastic restraint stiffness of the web member provided by the bottom chord would not increase by increasing the tension of the bottom chord within the range of elastic deformation. The elastic restraint stiffness of the web member provided by the top chord would not weak by increasing the pressure of the top chord within the range of elastic deformation. It was recommended that the effective length factors of the support and other web members of the steel truss should be 0.8 and 0.7, respectively.

在钢结构设计规范中，由双角钢组成的钢桁架的支座和其他腹板构件的有效长度因子分别为1.0和0.8。但是，支撑和其他腹板构件的有效长度系数未考虑诸如非相邻构件所提供的刚度，接头本身的刚度以及载荷变化对钢设计规范的影响等因素。结构。考虑到上述影响因素，在Abaqus中建立了基于钢桁架图谱的有限元模型，并通过数值分析获得了腹板构件端部的弹性约束刚度。根据腹板构件端部的约束建立方程，用Matlab求解方程，求得腹板构件的有效长度因子。分析发现，由底弦提供的腹板构件的弹性约束刚度不会通过在弹性变形范围内增加底弦的张力而增加。通过在弹性变形的范围内增加顶弦的压力，由顶弦提供的腹板构件的弹性约束刚度不会变弱。建议将钢桁架的支撑和其他腹板构件的有效长度系数分别设置为0.8和0.7。分析发现，由底弦提供的腹板构件的弹性约束刚度不会通过在弹性变形范围内增加底弦的张力而增加。通过在弹性变形的范围内增加顶弦的压力，由顶弦提供的腹板构件的弹性约束刚度不会变弱。建议将钢桁架的支撑和其他腹板构件的有效长度系数分别设置为0.8和0.7。分析发现，由底弦提供的腹板构件的弹性约束刚度不会通过在弹性变形范围内增加底弦的张力而增加。通过在弹性变形的范围内增加顶弦的压力，由顶弦提供的腹板构件的弹性约束刚度不会变弱。建议将钢桁架的支撑和其他腹板构件的有效长度系数分别设置为0.8和0.7。