RHTPE
Structural
- Jun 11, 2008
- 702
Okay folks, I'm looking for your thoughts on this one.
Related thread:
I have a single slope PEMB frame that experienced extreme snow load this past winter. Both columns bear on a 10" wall extending 48" about the floor (we all know that's not smart, so don't go there). No pilaster under the columns, only 2 out of the 4 anchor bolts were installed. I would bet there's no reinforcing in the wall. The horizontal load at the base of the taller column cracked the 3'-3" wide, 10" thick wall at the floor line and temporarily pushed it out about 2". This wall is between 2 overhead doors. After the roof was cleared and the the weather warmed up, the wall almost returned to its original position.
My question for those with more experience with PEMBs than me: Analysis shows that if the bottom of either column is allowed to move in the horizontal direction, the maximum positive moment in the roof beam increases to about 140% of the fixed column base condition. What kind of weakening of this frame could have occurred? There was no collapse, just damage to the foundation wall at one end.
I will be examining all bolted connections this week (haven't done so yet because of the height) to look for distortions around the bolt holes. I have also posed the same question to the PEMB manufacturer. This has been lingering while we wait for the owner's insurance company to determine what they want to cover. I am advocating rebuilding the wall and foundation at each end of the frame to accommodate all design forces applied by the columns. I sense that the insurance company only wants to cover the failed wall and nothing else.
I will save the editorial comments about residential foundation contractors (who built the foundation) and semi-retired builder inspectors (who asked for a foundation design by a P.E. but didn't follow through).
Ralph
Structures Consulting
Northeast USA
Related thread:
I have a single slope PEMB frame that experienced extreme snow load this past winter. Both columns bear on a 10" wall extending 48" about the floor (we all know that's not smart, so don't go there). No pilaster under the columns, only 2 out of the 4 anchor bolts were installed. I would bet there's no reinforcing in the wall. The horizontal load at the base of the taller column cracked the 3'-3" wide, 10" thick wall at the floor line and temporarily pushed it out about 2". This wall is between 2 overhead doors. After the roof was cleared and the the weather warmed up, the wall almost returned to its original position.
My question for those with more experience with PEMBs than me: Analysis shows that if the bottom of either column is allowed to move in the horizontal direction, the maximum positive moment in the roof beam increases to about 140% of the fixed column base condition. What kind of weakening of this frame could have occurred? There was no collapse, just damage to the foundation wall at one end.
I will be examining all bolted connections this week (haven't done so yet because of the height) to look for distortions around the bolt holes. I have also posed the same question to the PEMB manufacturer. This has been lingering while we wait for the owner's insurance company to determine what they want to cover. I am advocating rebuilding the wall and foundation at each end of the frame to accommodate all design forces applied by the columns. I sense that the insurance company only wants to cover the failed wall and nothing else.
I will save the editorial comments about residential foundation contractors (who built the foundation) and semi-retired builder inspectors (who asked for a foundation design by a P.E. but didn't follow through).
Ralph
Structures Consulting
Northeast USA
