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Re: ANSI/TIA-222-G-2005

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Fellow engineers,
        Perhaps one of you could educate me regarding the "Directionality Factor" indicated by Ed in the posting below.  I'm interested in the basics behind this factor rather than anything code specific for the obvious reason that I don't live in a location governed by the code.
        I've always had the opinion that the design level wind loading resulted from high speed winds surrounding a low pressure storm centre and, hence, could come from any direction (unless, of course, you are located in a mountain valley, in which case it could only come from up or down the valley.
Thanks for your indulgence.
H. Daryl Richardson
----- Original Message -----
Sent: Tuesday, June 27, 2006 12:13 PM
Subject: Re: ANSI/TIA-222-G-2005

One of the big differences is the "Directionality Factor".  See ASCE 7-05 Section 6.5.3 (1) for the start of the procedure.  The higher wind load factor is partially compensated by the addition of the Directionality Factor.

Ed Haninger

Drew Morris <dmorris(--nospam--at)>
06/27/2006 10:52 AM
Please respond to seaint
Re: ANSI/TIA-222-G-2005

Both ASCE 7 -02 and 7-05 have 1.6W in the basic load combination using strength design.  The 1.3W used to be in the older alternative basic load combination (ASD) in the 2003 and older IBC.

G. Bunkers wrote:

The lastest version of the code for towers - TIA-222-G-2005 has went to
Limit State design and shows the following load combinations:
1. 1.2D + 1.0 Dg + 1.6 Wo
2. 0.9 D + 1.0 Dg + 1.6 Wo
3. 1.2 D + 1.0 Dg + 1.0 Di + 1.0 Wi + 1.0 Ti
4. 1.2 D + 1.0 Dg + 1.0 E
5. 0.9 D + 1.0 Dg + 1.0 E
My question is why the 1.6 factor for wind.  ANSI / ASCE
states  1.3 .
Gary Bunkers P.E.

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