Existing Building Steel Plumbness
Apr 29, 2021
17
| STATEMENT OF PROBLEM: One of the main portions of work that we were tasked to complete was building a 120,000 square foot addition that directly tied into the existing plant. Unbeknownst to the project team at bid time, the existing building columns were out of plumb and leaning away from the addition. The first row of columns and trusses were erected per the plan and all connections were tightened completely. The remaining columns and trusses were erected for the first two sequences of steel and the ironworker team proceeded to detail out this entire section. At this point, all new columns were out of plumb, and the entire building needed to be racked to bring everything into plumb. Field measurements/survey inside was difficult due to limited access from the inside due to process equipment/production. COURSE OF ACTION: Due to schedule constraints, a decision was made in the field to erect the building as quickly as possible and then circle back to detail, square, and plumb everything as bays of steel were completed. This allowed shim plates to be fabricated and installed in the field to correct the out of plumb building columns. The customer reimbursed CCC for a portion of the extra time that was spent on modifying the connections in order to bring the building back to plumb. LESSON FOR FUTURE PROJECTS: When tying into existing building steel, a steel survey needs to be completed on the column steel to verify plumbness / levelness. The survey needs to be included within the steel erector''''s SOW along with their anchor bolt survey. If CCC-Steel cannot provide this or determines there''''s risk then a 3rd party survey should be performed. The first bay off of the building needs to be plumb and aligned before the sequence is continued. Also noted that when performing steel erection need to have anchor bolts meet AISC tolerances, not concrete tolerances. AISC tolerances are more stringent than concrete, and this is typically noted on the struc general notes drawing sheet. |
