Post-Buckling Analysis of Steel Space Trusses

A methodology is developed to perform nonlinear postbuckling analysis of steel space truss systems. Structural behavior is modeled at the element level through appropriate stress-strain relationships. Nonlinearities due to member buckling or yielding are modeled using a tangent modulus in the evaluation of the element elastic stiffness matrix. First-order geometric effects-are included using a geometric stiffness matrix. Second-order effects are included through a corotational coordinate transformation formulation. An incremental iterative solution strategy utilizing modified Newton-Raphson iterations with a constant arc-length constraint is presented. Both pre- and postcritical regions of the structure load-deflection path can be traced with the strategy. Results are obtained and compared for linear and nonlinear material behavior along with second-order geometric nonlinearity. The generated results provide information on the failure mechanisms most critical to a particular truss system, and techniques which can be used to reduce the effects of the failure mechanisms are described.