Pre-erection: verify anchor bolt locations ±1/8 in (AISC Code of Standard Practice). Set base plates and level with grout or leveling nuts. Erection sequence: 1) Set columns — lift with crane, guide with tag lines, seat on anchor bolts, install 2 nuts finger-tight. 2) Plumb and brace columns — use cable guys or frame to stabilize. 3) Set beams/girders — connect to columns with erection bolts (min 2 per connection). 4) Install bracing — permanent or temporary. 5) Plumb and align — transit/laser for verticality ±1/500 height. 6) Final bolt-up — replace erection bolts with permanent (snug-tight, pretensioned, or slip-critical per engineer). 7) Install decking — metal deck welded or mechanically fastened, pour concrete fill. Safety: OSHA Subpart R, fall protection, controlled decking zone. Crew: raising gang (4-6 ironworkers), crane operator, signal person, connector, bolter-up, plumber-up. Productivity: 10-20 tons/day typical.