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wind load on fences/walls

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It is funny what brings on the most responses on this list, normally beer and politics are the hot buttons..... With fences, a definite "where are the bodies?" comes to mind. However, at the begining of my career there was locally an incorrectly designed CMU screen wall that killed a landscaper who was digging a hole for irrigation near or under the footing. It was found to have a very small and inadequate footing, that if correctly designed and built may have prevented the overturning. But during your average wind event you are not taking cover adjacent to your nearest fence or CMU wall.
 
During severe wind events, open fences such as wrought iron, wood and vinyl picket type fences, and CMU and unreinforced brick walls failed en masse (my experience here in Florida and in Mississippi). Saturated sandy soils do little to resist a post in overturning it seems, and very few people put wood posts in concrete. Little attention is paid to these as many did not or do not require any engineering to begin with, though that must have changed as we design reinforced CMU screen walls all of the time and they require engineered drawings. But I have not been asked to design a wood fence, think that is prescriptive somewhere in the code.
 
I think off the top of my head (not near a reference) for V=120mph we usually end up with about +/- Plat= 25psf. We use ASCE free-standing walls to determine the pressure, closest thing in any code we are aware of.
 
Currently, the HWVZ (S Florida) section of code has prescriptive designs for wood fences under 6ft. I know this is only S Florida but it is just FYI:
 
SECTION 2328 HIGH-VELOCITY HURRICANE ZONE?WOOD FENCES

http://www2.iccsafe.org/states/florida_codes/
 
 
HTH,
Andrew Kester, PE
Orlando, FL
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