Verification of Member and Gusset Plate Imperfections in GMNIA Simulation

Abstract

Gusset plates are commonly used in the design and construction of trusses and bracing systems. A major design challenge is addressing the combined stability failure of the gusset plate and the steel member, which current design specifications tend to treat separately, overlooking their interaction. Although engineering models exist for designing columns with gusset plate connections, they are not widely adopted and may yield conservative or unsafe results. Numerical tools, including complex non-linear shell finite element methods, offer a more robust solution but are error-prone and require deep problem knowledge. Recently, component-based finite element methods (CBFEM) have gained popularity, enabling detailed simulations of entire systems, including members and gusset plates. A key aspect is selecting the appropriate imperfection shape, often derived from linear buckling analysis (LBA), which significantly influences the load-bearing capacity in a GMNIA (geometrically and materially nonlinear analysis with imperfections). The paper proposes criteria for choosing imperfection amplitudes in gusset plate connections, supported by CBFEM simulations and comparisons with experimental data from the literature.