13.18: Advanced analysis of braced steel frames: Modelling accounting for the post‐limit behaviour of compressed angle braces

ABSTRACT This paper presents a method of advanced analysis applied to steel plane load bearing systems like trusses as well as unbraced and braced frames. The effects of both material and geometrical nonlinearities on the structural behaviour are studied together with tracing the whole range of truss member behaviour. In the braced frameworks, the truss bracing model accounts for the effect of post‐limit behaviour on the inelastic redistribution of forces in frame members. Details of finite element incremental stiffness matrices for frame members and truss bracing members are briefly presented and followed by the discussion how the effects of gradual yielding, buckling and semi‐rigid joints are included. The implementation into engineering computer software is summarized and followed by certain aspects of truss and frame structural systems design according to Eurocode 3. A simple two‐bar arch truss sensitive to the elastic snap‐through buckling for which the closed form solution exists is considered as an example. Simulations of the behaviour of this truss show how the nonlinear behaviour of a single member affects the global instability of the truss. Conclusions are formulated with reference to the application of advanced analysis in direct design of steel braced frameworks.