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RE: Alternate Wind Provision

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A couple weeks ago I listened to a web seminar, ASCE with CEU units through NSCEA.  The name of the seminar was “Designing Buildings for Wind Load by ASCE 7-05”.  In that seminar it was also indicated that the simplified method was for a “simple diaphragm building” with one of the criteria being  “…wind loads are transmitted through rigid floor and roof diaphragms.”  A question was asked of the speaker if this method would include flexible plywood diaphragms and the answer was “no”.

Joe Grill


From: Yousefi, Ben [mailto:Ben.Yousefi(--nospam--at)]
Sent: Tuesday, April 29, 2008 8:14 AM
To: seaint(--nospam--at)
Subject: RE: Alternate Wind Provision


The requirement (item 4 of the conditions) is a “simple diaphragm” as defined in ASCE 7 section 6.2. This doesn’t preclude flexible wood diaphragms. I believe the intent is to not include horizontal truss or cross bracing rods such as those used in metal (Butler type) buildings.

Ben Yousefi, SE, CBO

Chief Building Official

City of Mountain View, CA

(650) 526-7007


From: Joseph R. Grill [mailto:jrgrill(--nospam--at)]
Sent: Tuesday, April 29, 2008 8:02 AM
To: seaint(--nospam--at)
Subject: RE: Alternate Wind Provision


I took a quick look at this.  The last paragraph in the “Committee Reason” says “The method should probably be limited to rigid diaphragms”.  Even though the word “probably” has been included, does this mean that the method cannot be used with smaller residential, or custom residential structures?

Doesn’t seem to help that part of the industry.

Joe Grill


From: Martin Li [mailto:mli(--nospam--at)]
Sent: Tuesday, April 29, 2008 7:36 AM
To: seaint(--nospam--at)
Subject: RE: Alternate Wind Provision



-----Original Message-----
From: Jerry Coombs [mailto:JCoombs(--nospam--at)]
Sent: Tuesday, April 29, 2008 8:44 AM
To: seaint(--nospam--at)
Subject: RE: Alternate Wind Provision

Was there any further discussion or update on this?  Where does one get a copy of S84?

>>> On 3/12/2008 at 12:29 PM, "Ehrlich, Gary" <gehrlich(--nospam--at)> wrote:

Trying to get my Inbox cleaned up…


I wanted to note that the IBC-Structural committee voted to approve the NCSEA version of the simplified wind procedure (S84, with minor modifications), over the SEAOC version (S85). The debate was extensive, but it did appear that one of the primary factors in the final decision was that the NCSEA version was a fully stand-alone method. The SEAOC method referred to the ASCE edge and corner zones but did not incorporate the ASCE 7 figures. Also there was much discussion of how both methods incorporated the internal pressure coefficients. The final vote was very close: 7-6 I believe.


I'm at an ASCE 7 wind subcommittee meeting right now; we're going to be discussing the proposal further with NCSEA later today.



Gary J. Ehrlich, PE
Program Manager, Structural Codes & Standards
National Association of Home Builders (NAHB)
1201 15th Street, NW, Washington, DC 20005
ph: 202-266-8545  or 800-368-5242 x8545
fax: 202-266-8369