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An energy dissipating hold down device for cold-formed steel structures

A two-phase experimental investigation has been conducted for the development and evaluation of a hold down device that has energy dissipating feature. Focus of the first phase was the development of the device itself, while the second phase concentrated on the investigation of the performance of this device when used in a CFS framed sheathed wall panel that is subjected to reversed cyclic lateral loading. Hold down subassembly test results indicate that the load capacity of the hold downs is mostly limited by the shearing capacity of connection screws. Hold down devices themselves were observed to remain virtually undamaged under center dot tensile loading, indicating a superior mechanical behavior in terms of strength and stiffness. As part of the second phase of the study, cyclic lateral load tests were conducted on seven CFS framed sheathed wall panels in order to study the energy dissipation ability of the proposed hold down device when used in CFS wall systems. Aligned with this focus, the anchor rods used to connect the hold downs to the foundation system in wall panel specimens were altered mainly by reducing the rod diameter within the middle portion over a certain length to provide controlled rod yielding under tensile forces. Controlled yielding of anchor rods was observed to reduce the drift demands imposed on wall panels due to seismic effects, resulting in a minimal damage on wall panels themselves