The In-Plane Effective Length Factor of Web Members of the Steel Truss

Abstract

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.