Structuralist.Net - Today's Construction Hall of Shame - Interior Braced Panels (prescriptive vs. full compliance)

• To: "SEAINT Listservice" <seaint(--nospam--at)seaint.org>
• Subject: Structuralist.Net - Today's Construction Hall of Shame - Interior Braced Panels (prescriptive vs. full compliance)
• From: "Structuralist" <dennis.wish(--nospam--at)gte.net>
• Date: Tue, 17 Apr 2001 00:39:56 -0700
• Cc: <aec-residential(--nospam--at)polhemus.cc>
Today we look at interior braced panels as allowed in UBC section 2320.11 and take a typical conventionally framed home in Wind region of 70-mph wind with Exposure C. Home is one story slab on grade and interior wall panel is spaced at the back of garage so that the maximum distance between braced walls from the front of the garage to the back of the house is no more than 40-feet. The wall at the back of the garage takes a wind load applied normal to the elevation of the exterior wall for 30-linear feet.

The Construction Hall of Shame (click on this link to launch) takes a typical 4-foot x 8-foot panel in this home and calculates the wind load by tributary area to the wall to check to see if the panels meet the code capacity based on the demand of the wind.

The conclusion raises to interesting questions. If the panels are inadequate (which they appear to be) then the prescriptive methods are a disaster waiting to happen. If the prescriptive method is correct, then our allowable values for shearwalls are much too low and the resistance to uplift by the virtue of the plate connection to the slab in shear and lack of tension ties is much greater than historic mechanics suggest. In other words if prescriptive construction is correct, we have been over designing home.

Visit our site and check the calculations for yourself. Do the numbers lie??????
http://www.structuralist.net/cgi-local/UltraBoard/UltraBoard.cgi?action="">

Regards,
Dennis S. Wish, PE
http://www.structuralist.net
AEC-Residential Listservice
(208) 361-5447 E-Fax
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