Progressive failure modelling and ductility demand of steel beam-to-column connections in fire

Following an illustrative case study of a two-bay by two-storey frame, the effect of ductility of connections on the collapse resistance of steel frames in fire is demonstrated in two case studies of a generic multi-storey frame. It is shown that the analytical process is an effective tool in tackling the numerical problems associated with the complex structural interactions and discontinuous failures which can affect a steel or composite frame in fire, potentially leading to progressive collapse. It can be seen that both tensile and compressive ductility in the connections make a contribution to the fire resistance of the beams. Preventing the detachment of steel beams in fire can be achieved by inducing greater ductility into their connections. Combined with appropriate component-based connection models, this procedure can be adopted in performance-based fire-resistant design to assess the ductility requirements of steel connections.