I think we are actually in agreement on this Steve. The reasons you spelled out are additional reasons I would NOT hang, brace, or restrain from the bottom chord unless no other location is feasible.
Ryan Hinson Burns & McDonnell Direct: 952-656-6003 Ext 3662 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Steve Leyton Sent: Thursday, January 28, 2010 5:10 PM To: [email protected] Subject: RE: Hanging. bracing, or restraining from the bottom chord of a truss or joist I should add that one BIG exception to my previous posting has to do with installation conforming to the manufacturer's installation guide for products like TrusJoists. They have several different approved means of connecting to the bottom of TJI's, but you'll note in their guidebook that other joist types DON'T include bottom chord attachment standards and sway bracing can NEVER be attached to the bottom. Steve Leyton Protection Design & Consulting San Diego, CA -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Steve Leyton Sent: Thursday, January 28, 2010 3:00 PM To: [email protected] Subject: RE: Hanging. bracing,or restraining from the bottom chord of a truss or joist Not sure where you heard that, but my training and understanding have been just the opposite. The bottom chords and surfaces of solid and manufactured members maintain the integrity of the piece through tension. Load it or cut it or bore into it along the bottom and you're digging at the Achilles Heel, so to speak. The only jurisdictional mandates I've ever encountered to hang to the bottom have come from State of California (no surprise here) engineers who have required that we hang from the bottom chord of steel beams in order to utilize a symmetrical beam clamp; believe it or not, they won't allow top beam clamps that hang from one side without an engineering analysis of the eccentric loads (!!) which is an expensive hassle and we've just abandoned fighting them. But except for that we very rarely connect to the bottom chords of anything, and only after close coordination with - and often specific written approval from - structural engineers of record and/or the manufacturer of the piece(s) in question. Steve Leyton Protection Design & Consulting San Diego, CA -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Hinson, Ryan Sent: Thursday, January 28, 2010 2:54 PM To: '[email protected]' Subject: Hanging. bracing, or restraining from the bottom chord of a trussor joist I have always been instructed to hang, trapeze, or brace to the top chord of trusses, joists, and other structural members. I believe it is good practice to do so since the top chord is restrained via the attached roof from lateral movement whereas the bottom chord is not except where cross bracing is attached. That being said, is there any specific code reference that mandates this; or is it strictly up to the structural engineer to determine whether the bottom chord can handle the possible generated loads? Ryan L. Hinson, EIT, NICET III Fire Protection Systems Designer, Aviation and Facilities Group Minneapolis-St. Paul Office Burns & McDonnell 8201 Norman Center Drive, Suite 300 Bloomington, MN 55437 Direct: 952-656-6003 Ext 3662 Fax: 952-229-2923 www.burnsmcd.com<BLOCKED::www.burnsmcd.com> Proud to be one of FORTUNE's 100 Best Companies To Work For _______________________________________________ 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) __________ Information from ESET NOD32 Antivirus, version of virus signature database 4815 (20100128) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 4815 (20100128) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com _______________________________________________ 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) __________ Information from ESET NOD32 Antivirus, version of virus signature database 4815 (20100128) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 4815 (20100128) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com _______________________________________________ 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) _______________________________________________ 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)
