A hollow section is a steel profile with a hollow square or rectangular cross-section, generally produced by forming hot-rolled sheet and welding it longitudinally. Being hollow gives it a high second moment of area for its weight.
That is why it is one of the most used sections in steel construction, in railings and in machine frames.
Technical specifications
| Square section | 20×20 – 300×300 mm |
|---|---|
| Rectangular section | 20×40 – 400×200 mm |
| Wall thickness | 1.00 – 12.00 mm |
| Grade | S235JR, S275JR, S355JR |
| Standard | EN 10219 |
| Length | 6,000 / 12,000 mm |
Square or rectangular?
A square section gives equal strength in two directions; it is preferred for members such as columns that take load from every direction.
A rectangular section gives higher strength in one direction; it is more efficient for members such as beams that take load from a particular direction.
Choosing the wall thickness
Wall thickness ranges from 1.00 to 12.00 mm. A thin wall gives lightness and a cost advantage, but increases the risk of buckling.
A thick wall gives higher load capacity at the same outside dimension. The choice follows the structural calculation.
The grade codes
The difference between S235JR, S275JR and S355JR is the yield strength (235, 275 and 355 MPa respectively). "JR" indicates the impact toughness class.
S235JR is common in general fabrication; S355JR is preferred in load-intensive structures and can do the same job with a smaller section.