AESS is an acronym for architecturally exposed structural steel. AESS is exposed to regular view by pedestrians or occupants of a building. Because it is clearly visible AESS is subject to closer tolerances than standard structural steel that is hidden from view.
I have been seeing more and more drawings requiring structural steel bending with architecturally exposed structural steel. I personally always get really excited every time I see this because I know people will be able to see our work and really appreciate curved steel as an architectural art form.
Tube bending of structural steel, such as square or rectangular tubes, is difficult. It is especially hard to keep deformation low on large tubes. No real tolerances are ever given on acceptable deformations. The individual steel sections that must conform to AESS tolerances must be clearly identified on the drawings so the fabricator knows which pieces must meet the more stringent requirements.
So as the sales person I am always asking my customer (the fabricator) what is acceptable. The majority say they don’t want to see ripples, bumps, dents, very deep gouges and other surface imperfections. Basically they want us to curve the tube using techniques that would maintain the original state of the tube without their having to spend any time on post-curve finishing. We have the expertise and special tooling to maintain the shape and structural integrity of the steel section. I also sometime advise low-deformation suggestions such as increasing the wall thickness or changing the tube to a channel with a welded plate to make a tube shape.