Why hollow sections dominate commercial construction

A square or rectangular hollow section resists bending and torsion more efficiently per kilogram than an open section like an angle or channel, which is why commercial framing has moved toward them over the last two decades.

They also weld cleanly on all four faces, which speeds up fabrication and gives architects a flush, exposed-steel look without extra cladding.

The tradeoff is availability — hollow sections come in fixed standard sizes, so drawings need to be finalized against a size chart early rather than assuming a custom dimension is easy to source.

Connection design also looks different from open sections — bolted connections typically need internal stiffening plates or through-bolts since there's no accessible flange to bolt to directly, so it pays to involve your fabricator before the structural drawings are frozen.