bouk715
Structural
- Apr 24, 2005
- 59
A 3-story steel framed building that I designed is currently in construction. Lateral resistance for the structure are braced frames.
We were called out to the site because at one location, a column is out-of-plumb 3" within the first story. The column does not appear deflected over this length, just leaning to one side. The building is already framed and floor slabs are in place. The movement was noticed when a stud wall was being framed in front of the column. Architectural pilasters have been built around the columns on the second and third floors, so I can't tell if the column is deflected or out of plumb over those lengths. Since the pilasters were built, I'm assuming that the column is reasonably (within AISC tolerances) plumb on the upper stories. I've requested the steel survey to see if this is the case. We have the foundation survey, and the footing is in the correct location.
I've analyzed the column for the P-delta effect caused by the movement, and it still works. I just have additional lateral forces I need to transmit into the rest of the structure. However, I believe I need to determine possible residual stresses in the column caused by bending. My assumption is that the movement occurred during erection and before the floor deck/slabs were in place. I'm hoping that the survey will confirm that. What is the best way to determine these stresses? I've modeled the column with imposed deflections - is this an acceptable approach? Or should I specify some form of testing? Just wondering what the typical approach is to this problem (if there is one).
We were called out to the site because at one location, a column is out-of-plumb 3" within the first story. The column does not appear deflected over this length, just leaning to one side. The building is already framed and floor slabs are in place. The movement was noticed when a stud wall was being framed in front of the column. Architectural pilasters have been built around the columns on the second and third floors, so I can't tell if the column is deflected or out of plumb over those lengths. Since the pilasters were built, I'm assuming that the column is reasonably (within AISC tolerances) plumb on the upper stories. I've requested the steel survey to see if this is the case. We have the foundation survey, and the footing is in the correct location.
I've analyzed the column for the P-delta effect caused by the movement, and it still works. I just have additional lateral forces I need to transmit into the rest of the structure. However, I believe I need to determine possible residual stresses in the column caused by bending. My assumption is that the movement occurred during erection and before the floor deck/slabs were in place. I'm hoping that the survey will confirm that. What is the best way to determine these stresses? I've modeled the column with imposed deflections - is this an acceptable approach? Or should I specify some form of testing? Just wondering what the typical approach is to this problem (if there is one).