Holdown (holdown, hold-down, or hold down) or tie-down in structural engineering refers to the steel device or hardware that is installed at the end of a plywood shear wall. The hold downs provide uplift resistance against the overturning moment imposed on the wall due to "in-plane" lateral load applied at the top of the wall. A hold-down may also refer to clamping device used to anchor a pipe to a structural steel element or concrete floor or allow movement of the pipe in an axial direction.[1]
At the bottom, the hold down is connected to the concrete foundation or structural slab by an embedded or epoxied anchor bolt. At the top, the hold down is connected to a wood post with screws, nails or bolts.