Seismic Damage Avoidance Design of Moment Resisting Frames Using a New Self‐Centering Friction Connection System
Moment-resisting frames are one of the efficient lateral-load resisting systems in terms of providing architectural freedom in design and widely distributing the seismic forces within the structure and into the foundation. Recent major earthquakes have resulted in significant plastic deformations in the beams, columns and connections causing irrecoverable damage in structures. As a result, engineers have focused on developing new systems which not only provide the life-safety of the residents but also minimise the damage such that the building could be reoccupied quickly after severe events with minimal business interruption and repair costs. In this research, a self-centring damage avoidance concept using an innovative Resilient Slip Friction Joint (RSFJ) is developed for steel Moment Resisting Frames (MRFs). The RSFJ provides the self-centring behaviour as well as energy dissipation in one compact component requiring no post-event maintenance. In this concept, the beam is connected to the column using a pin assembly at top, and the RSFJs acting in tension and compression at the beam bottom. The RSFJs allow for the gap opening in the connection during loading and re-centre the system upon unloading. Furthermore, a secondary collapse-prevention fuse within the RSFJ is considered to keep maintaining ductile behaviour in the system in case of an event greater than the design earthquake. In this research, an analytical model was developed to accurately predict the moment-rotation behaviour of this system. The seismic performance of the proposed concept was investigated by a full-scale beam-end connection test. The tests results validate the predictive model and demonstrate the efficiency of this new self-centring system for the seismic damage avoidance design of MRFs.