Assessment of progressive collapse in multi-storey buildings

A simplified framework is proposed for the progressive collapse assessment of multi-storey buildings, considering sudden column loss as a design scenario. This framework can be applied at various levels of structural idealisation, and enables the quantification of structural robustness taking into account the combined influences of redundancy, ductility and energy absorption. Three main stages are involved in the proposed approach: (a) determination of the non-linear static response, (b) dynamic assessment using a novel simplified approach based on energy conservation and (c) ductility assessment at the maximum dynamic deformed configuration. The application of the proposed method is illustrated on a multi-storey steel-framed composite building, where the relative importance of various joint details and levels of axial restraint are highlighted. Importantly, the study underlines the inadequacy of prescriptive tying force requirements that neglect ductility issues, and demonstrates that typical composite buildings must rely on bending or compressive arching rather than tensile catenary action for enhanced structural robustness.