Automated linear buckling analysis of space frame structures

This article presents a streamlined procedure for assessing the capacity of space frame structures by incorporating geometric (stress) stiffness directly into the structural analysis. The procedure, implemented in the software SeaWare, employs novel techniques for handling hydrostatic pressure and assessing initial imperfections. It ensures full compliance with NORSOK design standards while accounting for second-order effects. Unlike conventional approaches that rely on the buckling length factor k and moment reduction factor Cm, the proposed procedure derives equivalent imperfections directly from the eigenvalue solution, calibrated against the governing buckling curve. This eliminates the need for manual parameter estimation and enables fully automated evaluation of all components across numerous load cases. The formulation combines the elastic and geometric stiffness matrices, F=(Ke+Kg)d, and applies an eigenmode-based scaling of imperfections consistent with design code principles. It provides a transparent and computationally efficient alternative to geometrically and materially nonlinear analyses (GMNA). By integrating these elements into a unified framework, it establishes a consistent and computationally robust foundation for code-compliant analysis of complex offshore structures and is presented in sufficient detail to enable direct implementation and reproducibility.