Advanced Analysis of Plane Steel Frame Having Imperfect Elements

Imperfect elements having initial curvature are usually used in construction and erection of the structures. In this paper, the explicit stiffness matrix for imperfect element is derived. The nonlinear tangent stiffness matrix of the beam-column subjected to the axial force, nodal moments and the lateral uniformly distributed load is calculated. Based on this matrix, advanced analysis of the plane steel frame is performed. Both tensile and compressive axial loads are also taken into account by one formula. By using the proposed stiffness matrix, the load-displacement curve is compared with the accurate plastic region methods, and in the most cases, good agreement is found. Comparing the obtained results with other references shows the accuracy and capabilities of the new formulation in evaluation of the steel frame load capacity having inelastic second-order behavior.