Strut

A strut is a structural component commonly found in engineering, aeronautics, architecture and anatomy. Struts generally work by resisting longitudinal compression, but they may also serve in tension.

A stay is sometimes used as a synonym for strut, but some sources distinguish that struts are braces for holding compressive forces apart, while stays are braces for keeping stretching forces together.

Part of the functionality of the clavicle is to serve as a strut between the scapula and sternum, resisting forces that would otherwise bring the upper limb close to the thorax. Keeping the upper limb away from the thorax is vital for its range of motion. Complete lack of clavicles may be seen in cleidocranial dysostosis, and the abnormal proximity of the shoulders to the median plane in cases of this genetic condition exemplifies the clavicle's importance as a strut.

Strut is a common name in timber framing for a support or brace of scantlings lighter than a post. Frequently struts are found in roof framing from either a tie beam or a king post to a principal rafter. Struts may be vertically plumb or leaning (then called canted, raking, or angled) and may be straight or curved. In the U.K., strut is generally used in a sense of a lighter duty piece: a king post carries a ridge beam but a king strut does not, a queen post carries a plate but a queen strut does not, a crown post carries a crown plate but a crown strut does not.

Strutting or blocking between floor joists adds strength to the floor system.

Struts provide outwards-facing support in their lengthwise direction, which can be used to keep two other components separate, performing the opposite function of a tie.^{[clarification needed]}

In piping, struts restrain movement of a component in one direction while allowing movement or contraction in another direction.

Strut channel made from steel, aluminium, or fibre-reinforced plastic is used heavily in the building industry and is often used in the support of cable trays and other forms of cable management, and pipes support systems.