عنوان مقاله [English]
نویسندگان [English]چکیده [English]
The collapse of a compression member gives rise to decrease of the load carrying capacity of the member. To perform a nonlinear analysis, in addition to the precritical behavior, the post-critical behavior of the compression member also must be determined. In this study, because of certain advantages of the finite element method, this method has been selected to evaluate the axial load-axial displacement relationships of the compression members. For determining the behavior of a pinended member using finite element method, the following observations have been considered: an elastic-pefectly plastic material behavior is assumed; the intial curvature associated with the bowing of the member has been considered as an initial imperfection; each member has divided into ten element and behavior of each element has been modeled by the Kirchhoff thin beam element; both of the material and geometrical nonlinearity has been considered in the analysis; to trace the equilibrium path through a critical point into the post critical range, the Arc-length method is used. The member type most commonly used in space structures is circular hollow (tubular) section and the present study is limited to the investigation of the post-critical properties of compressive tubular members with various selenderness ratios and also various imperfections.