Thursday, December 18, 2008

Re: Wind Load on Wood Fence

I thought fences taller than 6 feet required a permit in most jurisdictions?  i.e.  why bother stressing the hamster-in-the-wheel even more over "design" wind forces?  Most fences, I'd say 85.284673057856%, fail due to rotted connections, poor maintenance, dynamic vehicular impact, etc...

On Thu, Dec 18, 2008 at 10:13 AM, Thor Tandy <vicpeng@telus.net> wrote:
Ahh.  I am found out!  OTOH ... what is wind load but a windstorm?

Thor A. Tandy P.Eng, C.Eng, Struct.Eng, MIStructE
Victoria, BC
Canada

-----Original Message-----
From: Bill Allen [mailto:t.w.allen@cox.net]
Sent: Thursday, December 18, 2008 9:41 AM
To: seaint@seaint.org
Subject: RE: Wind Load on Wood Fence

But they didn't fail due to wind load, did they? They merely failed during a windstorm after the material had degraded.

 

Right?

 

T. William (Bill) Allen, S.E.

ALLEN DESIGNS

Consulting Structural Engineers
 V (949) 248-8588 • F(949) 209-2509

-----Original Message-----
From: Thor Tandy [mailto:vicpeng@telus.net]
Sent: Thursday, December 18, 2008 9:31 AM
To: seaint@seaint.org
Subject: RE: Wind Load on Wood Fence

 

When the base at ground level rots, about 100% ... mine did anyway  :^)

 

Thor A. Tandy P.Eng, C.Eng, Struct.Eng, MIStructE
Victoria, BC
Canada

 

-----Original Message-----
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.

ALLEN DESIGNS

Consulting Structural Engineers
 V (949) 248-8588 • F(949) 209-2509

-----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

 




--
David Topete, SE
at