Development of a ratcheting, tension-only fuse mechanism for seismic energy dissipation
Seismic damage-resistant structures, such as jointed precast connections and rocking wall structures, usually require supplementary energy dissipation devices to limit peak displacements. Yielding steel fuses or buckling restrained braces (BRBs) can provide energy dissipation but have a tendency to create residual compressive forces after joint closing that can resist the re-centring of the structure and fight the post-tensioning forces on subsequent cycles. A ratcheting, tension-only fuse device has been developed to offer resistance to loading in tension, while offering negligible resistance to compressive motion. This lack of compressive forces allows re-seating of a rocking connection to minimise residual structural displacements. Upon re-loading, fuse engagement will be more rapid due to the ratcheting mechanism, as the absence of residual compressive loads reduces the amount of elastic take-up before yielding occurs. A prototype ratcheting fuse mechanism with a yield force of 45kN and an ultimate tensile force of 65kN has been designed and experimentally tested. The design was refined to provide ease of manufacture, eliminating complex and expensive processes, to reduce the overall construction costs. Experimental proof-of-concept testing on six fuse elements demonstrated the function of the ratcheting mechanism and assessed the hysteretic behaviour of the fuse element and the overall device with two different tooth pitch sizes. High speed camera footage of the ratcheting mechanism was recorded to assess engagement timing.