A Computational Method for the Inelastic Postbuckling of Steel Space Structures with Bolt Slip

The nonlinear behavior of space structures has been researched by various authors using the total and updated Lagrangian formulations. In this paper, a corotated-updated Lagrangian (CR-UL) formulation is used for studying the postbuckling behavior of steel reticulated systems. This formulation is used since space truss elements contain large components of rigid body displacements. The global tangent stiffness is derived from the corotation (CR) principle and the local (natural) tangent stiffness is derived using the updated Lagrangian (UL) finite element formulation. A state determination procedure is used for including the inelastic behavior with mixed hardening. Here members are assumed to reach the material strength limit state, which is reasonable in large span space structures based on serviceability governed design, with no consideration made for member buckling. The effect of bolt slip in the member joints is included by using a sudden slip model under the service loads. The global nodal displacements and coordinates are updated based on the analytical model of the bolt slip displacement using a simple affine transformation. The effect of bolt slip on the global displacements and member forces has been studied and compared with the results of previous authors.