Development and Application of the Resilient Sliding Hinge Joint in New Zealand

The Sliding Hinge Joint with Asymmetric Friction Connection, to give the SHJ its full name, is a semi-rigid beam to column connection used in moment resisting steel frames for high seismicity applications. It is designed and detailed to be rigid under normal conditions and under moderate earthquakes, become flexible during a severe earthquake and become rigid again once the shaking stops. The SHJ was developed in New Zealand in the late 1990’s and has been used in buildings there since the mid 2000’s. The original joint fulfils the first two of these requirements very well, but, after significant sliding following a severe earthquake, the bolts that control the friction sliding lose significant installed bolt tension, as expected, so the threshold for sliding in a subsequent event is lowered, potentially necessitating bolt retightening. Since 2010, a very significant new development has involved incorporating partially deflected Belleville Springs under the head and the nut of the bolts controlling friction sliding, keeping these bolts in the elastic range as they are subjected to the double curvature moment demands generated by sliding of the asymmetric friction system. This enables at least 90% of the installed bolt tension to be retained following severe sliding, making the joints and the system resilient. As of February 2024, there are 5 buildings in New Zealand now under design, construction or completed using the OSHJ, as this new development is called. This paper tracks the development of the SHJ/OSHJ from its beginning, through to its current status as one of the more successful resilient seismic resisting systems used in New Zealand and describes the scope of past, current and planned future research into this innovative and cost-effective resilient seismic resisting system. It includes preliminary reports from a near full scale, 3 storey steel framed building with composite floors which has been tested on the large shake table array of the ILEE laboratory at Tongji University, Shanghai, China.