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.