Hollow section (SHS, RHS, CHS)
A hollow section is structural steel tube, square (SHS), rectangular (RHS) or circular (CHS), to AS/NZS 1163, used for posts, beams and bracing in residential steelwork.
Ask Chalkline about this →A hollow section is structural steel tube used as a load-carrying member. It comes in three shapes, square (SHS), rectangular (RHS), and circular (CHS), made to AS/NZS 1163, and it is common for posts, beams, lintels, and bracing in residential and light commercial steelwork.
Hollow sections are popular because the steel is distributed around the perimeter, which makes them efficient and stable, especially in compression and torsion. A square or circular hollow section resists buckling well in all directions, which is why they make good posts and columns. Rectangular sections, with more depth one way, suit beams and lintels where bending is mostly about one axis. They are specified by their dimensions and wall thickness (for example 89 x 89 x 3.5 SHS) and a steel grade (commonly C350 or C450).
A few practical points:
- Connections are usually welded (cleats, base plates, end plates) or bolted through, and the weld category is set by the engineer.
- Corrosion: being hollow, the inside can rust if water gets in and cannot drain or dry; galvanising and sealing or draining the ends matters, especially outdoors.
- Don’t drill or notch freehand: holes and their position affect capacity; they are part of the design, not site discretion.
For a builder the practical points are to use the size, shape, and grade specified (a hollow section is not interchangeable with a C-section or a universal beam without re-design), to get the connections fabricated to the engineer’s details and weld category, and to manage corrosion on exposed sections (drainage, end caps, galvanising, paint). Handle and store them so they are not bent, and protect cut or welded ends from rust.
Also known as: SHS, RHS, CHS, structural tube, box section.
Category: Materials / Structural steel.
Related
See also
References
- AS/NZS 1163 Cold-formed structural steel hollow sections, Standards Australia (verified 2026-06-04)
Last updated: 2026-06-04. Verified: 2026-06-04. Quarterly review for currency.