(hold-down, 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 holdowns provide uplift resistance against the overturning moment imposed on the wall due to "in-plane" lateral load applied at the top of the wall.
At the bottom, the holdown is connected to the concrete foundation or structural slab by an embedded or epoxied anchor bolt. At the upper end the holdown is connected to the wood post with screws or bolts.