Stirrup
A stirrup is a closed-loop or U-shaped steel bar fitted around beam longitudinal bars to resist shear forces. Spacing is engineer-specified per AS 3600:2018.
Ask Chalkline about this →A stirrup (also called a fitment or ligature) is a closed-loop or open U-shaped deformed bar fitted transversely around the longitudinal reinforcing bars in a concrete beam or column. Stirrups resist shear and torsional forces in concrete elements, confine the compression zone, and prevent the longitudinal bars from buckling outward under load.
On a residential job, stirrups appear in edge beams, internal beams (ribs), and ground beams where the engineer’s drawings specify transverse reinforcement. The steel fixer cuts and bends stirrups to shape, then threads them over the longitudinal bars and ties them in place at spacings shown on the drawings. Spacing is tighter near supports (where shear is highest) and may be more generous at mid-span. The engineer specifies this layout; the steel fixer is not permitted to interpolate or skip.
Stirrup spacings and cover to stirrups are checked at the mandatory pre-pour inspection. Because stirrups are typically the outermost element in the beam cage, the cover to the stirrup face governs the nominal cover requirement. Under AS 3600:2018, cover is measured to the nearest reinforcement face, which means the stirrup, not the longitudinal bar inside it (verified 2026-05-10).
Also known as: Fitment, ligature, link, shear tie.
Category: Structural / Reinforcement.
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Last updated: 2026-05-10. Verified: 2026-05-10. Quarterly review for currency.