A strut is a structural member specifically designed to resist compression forces, essentially being pushed together along its length, commonly used within trusses, as bracing, or as intermediate support in various framing assemblies where this particular type of force needs to be resisted.
This term is used broadly across construction and engineering, describing the functional role a member plays, resisting compression, rather than referring to a single specific product or location.
Because struts work in compression rather than tension, their design considerations focus particularly on preventing buckling, a failure mode specific to slender members under compressive load.
What Does a Strut Involve?
- Structural material sized to resist buckling under compression
- Placement within trusses, bracing systems, or other assemblies
- Connections capable of transferring compressive force
- Sizing accounting for both strength and buckling resistance
Why Are Struts Important?
Within a truss or bracing system, struts play a critical role resisting the compressive forces that would otherwise cause the overall structure to collapse or deform under load, working alongside tension members to create a stable, triangulated structural system. Understanding which members in a given assembly function as struts, resisting compression, versus which work in tension helps clarify how a complex structural system actually distributes and resists loads.
Because struts specifically need to resist buckling, a slender strut carrying significant compressive load may require a larger cross-section or additional lateral bracing along its length than a comparable member working purely in tension would need. This nuanced understanding helps engineers and builders alike design more efficient, reliable structures. This careful distinction between tension and compression roles underlies sound structural design generally.
Strut vs. Purlin
A strut is defined by its structural function, resisting compression, regardless of orientation. A purlin is defined by its specific application, providing horizontal intermediate support for roof sheathing between rafters, a more particular use case than the general compression-resisting role of a strut.