Effect of ductility of flush end-plate connections on the behaviour of MRFs under fire conditions: An experimental study

Abstract

The performance of beam-to-column connections is a key factor in the behaviour of moment-resisting frames (MRFs) under fire conditions. In this work, the behaviour and failure mechanisms of a half-scale 3D frame, composed of single-bay, single-storey MRFs and Braced Frames, in two perpendicular planes, equipped with 6 mm thick flush end-plate connections, under fire conditions was studied. A ‘scaled’ ISO 834 standard fire curve was followed during fire loading of the frame. The maximum reached temperature was 1100 °C. The temperatures of the elements of frames were measured at 2-minute time intervals. The rotations of the connections and the deflections of the MRFs’ beams at these time points were worked out using an image processing technique. Furthermore, the effect of the ductility of connections was investigated by comparing the results of this study with those of a previous one in which less ductile connections were used. The results showed that the connections used in this study could sustain large rotations of up to 0.7 radian and endure 65 min under fire. Moreover, it was found that using flexible connections (connections with thinner end-plates) enhances the ‘robustness’ of moment frames in fire.