Refined plastic-hinge model for analysis of steel-concrete structures exposed to fire

This paper is concerned with the application of a proposed approach, denoted as SAAFE Program (System for Advanced Analysis for Fire Engineering), developed to provide inelastic analysis of steel and composite (steel-concrete) 2D framed-structures exposed to fire. The method, although similar in concept to earlier plastic-hinge approaches, differs in relation to both numerical methodology and precision, allowing accurate description of the structural non-linear response with little computational effort, when compared to that of the general FEM formulation. The analysis is based on the two-level approach, in which the cross-section and member are continuously performing in an interactive way. The variation on member is performed by a transient heat-transfer analysis model, accounting for thermo-dependent properties of heated materials. A second-order plastic-hinge model is formulated in a succinct format considering yielding progress during fire and accurate identification of member instability. Obtained results for calibration examples are compared to those of the FEM approach, showing reasonable agreement. A proposed multi-storey composite framed structure is assessed by SAAFE, outlining the advantage of considering advanced analysis in the current fire-design practice of structures.

► Approach provides inelastic analysis composite 2d framed-structure under fire.
► Accurate description of non-linear response with little computational effort.
► Obtained results show reasonable agreement to fem approach.
► Able to perform multi-storey composite framed structures.