Direct design of steel framed structures by finite element analysis according to EN 1993-1-14

The design of steel structures has traditionally followed a two-step process involving a simple structural analysis to determine the internal forces and moments, followed by design checks to verify the resistance of the individual members. While long established in practice, this sequential process fails to capture key nonlinear and interaction effects, with its shortcomings becoming more pronounced with increasing structural complexity. Recent advances in computational tools, alongside the introduction of EN 1993‐1‐14, now enable a more integrated and accurate approach through geometrically and materially nonlinear analysis with imperfections (GMNIA). GMNIA offers the most comprehensive representation of structural behaviour by directly capturing the effects of instability, plasticity and imperfections within a unified analysis framework. This paper provides technical background and guidance in support of EN 1993‐1‐14, detailing a GMNIA-based design methodology using beam finite elements and strain limits. The essential components of GMNIA-based design include: (1) constitutive modelling for hot-rolled steel and cold-formed steel; (2) imperfections suitable for use in GMNIA; (3) consideration of local buckling on a full cross-section basis; (4) criteria for determining structural resistance, including strain limits to define cross-section resistance and deformation capacity in beam finite element models; and (5) consideration of the uncertainty associated with the adopted numerical model and analysis type through a model factor γ FE . The research presented forms part of the technical foundation of EN 1993‐1‐14 and supports the broader adoption of nonlinear, analysis-based design in structural engineering practice.