Steel structures buildings are faster in construction, versatile, simpler in structural behavior. Con is just economy and the insane precision required.It is extremely rare to see prestressing (mean external post-tensioning) in steel structures for the following reasons.
1) Steel is already extremely costly (you don't want to add cost of prestressing + anchorages to it)
2) Prestress does not last forever (creep, relaxation loss of prestress and corrosion protection will definitely add more recurring costs)
3) It is not cost effective. Unlike RC, having a couple of prestressing tendons will not add a significant capacity to the plastic section capacity of a class 1 steel section. It's much better to go for a higher section.
4) Better alternatives are available. Slim floor construction has many innovative approaches to achieve reduced floor thickness. Other than in "repair and rehabilitation" projects, I do not see any application for prestressing in structural steel construction projects. The elastic range of stresses is increased.
The only examples that I can think of is in the use of Friction Grip bolts for connections where the bolts are pre-torqued. But this is an example of its use in bolted connections, not for steel construction in general. I have encountered the use of camber in trusses but that is not strictly a pre-stressed steel structure. Possibly this is being used abroad.
It involves planning and producing during the fabrication and erection, by using tendons. Stresses of opposite magnitude to those anticipated during the life of the structure. If the paying client is willing to spend more money and if the contractor has the competence to execute it then there are some advantages like: Fatigue strength is increased, Deflections are reduced, stability is improved.
Residual stresses from welding, mechanical operations, temperature treatments are removed or utilised to off-set stresses due to the imposed loads during service.