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RE: Yet another Wind question

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"The tributary area of 700sf is not a part of the definition of MWFRS but is
a helpful exception that allows C&C elements with TA larger than 700sf to be
treated as MWFRS. As you say, if the intent is there then the rules should
be revised."

That is what we (or at least I) was talking about.  The point is the MWFRS
tables can end up getting used for MORE than just MWFRS pressures.  For C&C
items with large trib areas, you end up using the MWFRS pressures for C&C
purposes.

You are correct in that such an element would NOT be a MWFRS ELEMENT...it
would still be a C&C ELEMENT.  That distinction is determined by its
function as you pointed out.  But, the point was that some C&C ELEMENTS get
large enough that you use MWFRS PRESSURES to design it.

It is an important distiction even if it ultimately just semantics (you only
really care if it is a MWFRS or C&C element to determine which method is
used to determine pressures...thus, it matters little where you CALL an
element a MWFRS or C&C element if it ultimately using the MWFRS method to
get the wind design pressures).

Regards,

Scott
Adrian, MI

-----Original Message-----
From: Christopher Banbury [mailto:cbanbury(--nospam--at)arkengineering.net] 
Sent: Thursday, February 07, 2008 9:07 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Yet another Wind question


I don't think the trigger exists with respect to MWFRS. I have some older
posts about this here and on eng-tips. A structural element or system is
MWFRS depending on its function in the structure, not on its size. The
tributary area of 700sf is not a part of the definition of MWFRS but is a
helpful exception that allows C&C elements with TA larger than 700sf to be
treated as MWFRS. As you say, if the intent is there then the rules should
be revised.

Christopher Banbury, PE
President

Ark Engineering, Inc.
PO Box 10129, Brooksville, FL 34603
22 North Broad ST, Brooksville, FL 34601
Phone: (352) 754-2424
Fax: (352) 754-2412
www.arkengineering.net

-----Original Message-----
From: Mark Johnson [mailto:markajohn(--nospam--at)yahoo.com] 
Sent: Wednesday, February 06, 2008 10:00 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Yet another Wind question

Josh, Scott,

Thanks very much for the responses.  I hadn't noticed the 700sf trigger 
before.  If all of us are correct in our reading of this, it isn't a 
major problem.  But I gotta say if this is the intent of the code 
writers (which seems incredible), it sure is an screwy way to 
implement it.

MJ




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