A novel method to improve robustness of end plate connections at elevated temperatures using bolt sleeves

The robustness of steel frames during fire events is primarily controlled by the rotational capacity of beam to column connections. Higher values of rotational capacity allow the beam to develop catenary action which enhances the survivability of the steel frame. The present study proposes a novel device to increase rotational capacity of steel end plate beam-column connections at elevated temperatures. By inserting a steel sleeve with a designated length, thickness and wall curvature between the end plate and the washer, the load path between the end plate and the bolts can be interrupted, promoting a more ductile response. An analytical solution predicting the sleeve design parameters is also presented. It is concluded that the proposed device can significantly increase the rotational capacity of the end plate connection at elevated temperatures. Furthermore, a detailed numerical investigation on end plate connections with various failure modes concluded that the proposed sleeve device does not have any negative effect on the connection performance at elevated temperatures.