From: Bill Allen [mailto:t.w.allen@cox.net]
Sent: Thursday, December 18, 2008 6:03 AM
To: seaint@seaint.org
Subject: RE: Wind Load on Wood Fence
What percentage of wood fences fail due to wind load?
I'm just askin'.
T. William (Bill) Allen, S.E.
Consulting Structural Engineers
V (949) 248-8588 •
-----Original Message-----
From: Conrad Harrison [mailto:sch.tectonic@bigpond.com]
Sent: Wednesday, December 17, 2008 6:44 PM
To: seaint@seaint.org
Subject: RE: Wind Load on Wood Fence
How pedantic are your building officials? Here most engineers avoid working through the wind loading code. They know the general principle is to multiply a reference pressure (qz) by a net pressure coefficient (Cfig), from experience qz typically less than 1kPa (they may calculate lower value), and then they always use a net pressure coefficient of 1.2, most of the time it is conservative. For free walls and free roofs it can be too low.
I’ve seldom had their luxury of design and being over conservative. I generally have to push the wind load to the minimum, to evaluate some existing structure.
Regards
Conrad Harrison
B.Tech (mfg & mech), MIIE, gradTIEAust
mailto:sch.tectonic@bigpond.com
Adelaide
South Australia