I agree with Chris in as much as you suspend loads vertically from "Panel points", top or bottom is irrelevant. (Over load of points between panel points can cause distortion of the upper or lower cord and weaken the truss.) However the introduction of Lateral loads by seismic connections is a whole different animal. A truss that will support XX load per lineal foot in the vertical position when laid on its side deflects, the same as when a lateral load is applied.(Check out the Bow of a 60' truss when it's not picked up in the vertical position.)
Thom McMahon, SET Firetech, Inc. 2560 Copper Ridge Dr P.O. Box 882136 Steamboat Springs, CO 80488 Tel: 970-879-7952 Fax: 970-879-7926 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Chris Cahill Sent: Friday, January 29, 2010 9:21 AM To: [email protected] Subject: RE: Hanging. bracing, or restraining from the bottom chord of a trussor joist Back when I first got in the business this issue came up. Not too far from you is a little 'ol institution of higher learning known as the University of Minnesota. I spoke with 2 PhD Professors and our own City SE. All were in agreement. The caveat is a truss with similar top chord and bottom chord construction. The truss does not care where you hang from. The load are transferred the same within the truss. That's the point of the truss. With that information while AHJ for the City I didn't care provided the chords were the same. And most of what we see is same top and bottom chords. As a contractor now it doesn't come up too often where there is even the opportunity to hang from the bottom so we just go along to get along and everything is top chord. I did ask why some SE's and AHJ had issues hanging from the bottom. Lazy and/or ignorant was what I got back. You know how some PhD's can be, lol. Chris Cahill, P.E. Fire Protection Engineer Sentry Fire Protection, Inc. 763-658-4483 763-658-4921 fax _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
