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

摘要

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 de scription 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.