Improving Seismic Resilience Using Structural Systems with Friction-Based Fuses

Current seismic design codes do not consider the consequences of building damage on the post-earthquake recovery process. A basic life safety approach views the building as a discrete object but ignores the building's context within a community wholly affected by the same disaster. The future of structural seismic design will strive for improved post-disaster occupancy performance by protecting a majority of the building structure and eliminating the need for full demolition and replacement. An example of a structural system which places an emphasis on these ideas is the Pin-Fuse (TM) collection of seismic force resisting systems. These systems use slipping friction surfaces to simulate plastic hinges. By limiting "yielding" behavior to isolated friction surfaces, structural repairs after an earthquake may be as simple as replacing bolts and friction shims at specific connections. A summary of the Pin Fuse (TM) systems is presented, explaining how the concept of friction-based energy dissipation can be applied to moment frame connections, braced frames and link beams, and demonstrating how global structural behavior can be improved versus conventional systems by using sliding friction surfaces to increase damping and dissipate energy. Examples of potential Pin Fuse (TM) connections will show how systems can be detailed to account for reliable behavior at rotations beyond the limits of typical framing systems. Furthermore, an update of the current research into these systems is provided, including results from ongoing dynamic friction tests. These tests demonstrate reliable hysteresis behavior can be achieved using composite friction surfaces and friction forces can be confidently predicted.