Expansion anchor
Structural Fixings for Ductwork Systems BG 10/2010, By Glenn Hawkins, Published by BSRIA in 2010, states in relation to structural fixings based on friction: ‘Friction is the working principle of expansion anchors. When installing the anchor, an expansion force is created which produces a friction force between the anchor and the structural base material. Two types of expansion anchor can be distinguished: torque-controlled and displacement-controlled. Torque-controlled anchors are expanded by applying a defined torque, which draws a cone into a sleeve and presses the sleeve against the hole wall. Displacement anchors are expanded by driving a cone into the sleeve, thereby pressing it against the wall of the hole. Hole depth, hole diameter and anchor embedment depth are key criteria that affect performance of these fixings.’
--BSRIA
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