tpetsmith
Structural
- Apr 18, 2011
- 3
Hi: Thanks in advance for any help. This site has been an excellent go-to source for many questions I've had over the years.
My concern is the recent hurricane in northeast and the engineering and design of newly elevated home building support structures in both A and V zones. FEMA's guide appears to indicate that all of the overturning force, not uplift, is resisted equally by the windward wall anchors. They show calc's to indicate that the overturning vertical couple component is equally divided amongst the number of anchors on that side of the house. For many of the 2-story, 17 ft wide by 40 to 60 foot long homes on the shoreline I don't see how this is possible along the long building wall line.
We've always taken lateral wind load into the floor and ceiling/roof diaphragms and collected it in the end shear walls. I typically don't allow any interior walls to act as shear collectors since virtually all do not run full width or height of the structure. While obviously the lower half of the first floor wall will impart overturning for the windward anchor below it, the remaining 75 to 80% of load is being collected by the first and second floor ceiling structures and roof diaphragms.
I'm sure FEMA has a rational reason...but I just don't see it at this time.
Again, thanks in advance to all for any and all help.
My concern is the recent hurricane in northeast and the engineering and design of newly elevated home building support structures in both A and V zones. FEMA's guide appears to indicate that all of the overturning force, not uplift, is resisted equally by the windward wall anchors. They show calc's to indicate that the overturning vertical couple component is equally divided amongst the number of anchors on that side of the house. For many of the 2-story, 17 ft wide by 40 to 60 foot long homes on the shoreline I don't see how this is possible along the long building wall line.
We've always taken lateral wind load into the floor and ceiling/roof diaphragms and collected it in the end shear walls. I typically don't allow any interior walls to act as shear collectors since virtually all do not run full width or height of the structure. While obviously the lower half of the first floor wall will impart overturning for the windward anchor below it, the remaining 75 to 80% of load is being collected by the first and second floor ceiling structures and roof diaphragms.
I'm sure FEMA has a rational reason...but I just don't see it at this time.
Again, thanks in advance to all for any and all help.
