You're right on about all of that, but the lower chords of engineered members are more sensitive to loading because they serve to strengthen the piece by maintaining tension. The more you load and distort the bottom chord, the exponentially higher the overall impact to the member. That's why 98% of the factory details you see from truss manufacturers show connections to upper chords only. The lower chords are especially sensitive and that's why you have to proceed with so much care and coordination.
Steve Leyton Protection Design & Consulting -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Monday, December 18, 2006 9:28 AM To: sprinklerforum@firesprinkler.org Subject: RE: Hanging on bottom of Steel bar joists Roof members are generally designed for support of the roof as well as predicted dead load weights for snow, (where applicable) lights, sprinkler piping, and other utilities. It all depends on the facility and what is factored into the design of the roof support system. It's pretty much a given in most facilities that these above mentioned items as well as cable trays, conduits, plumbing piping and such will be hung from the roof steel. But for the most part, those items are attached to the top chord of the truss. Just need to check with the structural engineer or manufacturer of the joist to find out what was factored into determining the dead load weight for the steel and where the approved attachments points are. Craig L. Prahl, CET Fire Protection Group Mechanical Department CH2MHILL Lockwood Greene 1500 International Drive PO Box 491, Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 [EMAIL PROTECTED] http://www.lg.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Thomas Reinhardt Sent: Monday, December 18, 2006 12:16 PM To: sprinklerforum@firesprinkler.org Subject: RE: Hanging on bottom of Steel bar joists Hi Jim, I encountered this problem when I was doing an inspection. No storage should be hung from the joist. The joist is rated to hold up the roof only. This takes in consideration of snow loads etc... During fire conditions storage on the joist can cause early collapse. More info can be found by calling the Steel Joist institute. http://www.steeljoist.org/pages/default.asp?NavID=107 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Zimmerman Sent: Monday, December 18, 2006 10:15 AM To: sprinklerforum@firesprinkler.org Subject: Hanging on bottom of Steel bar joists Is there a specific rule somewhere that states Fire Protection pipe (or any mechanicals for that matter) cannot hang from the bottom chord/angle of a bar joist? My specific application is with 44 LH series joists. Thanks, Jim Zimmerman <http://www.designbuildfire.com/> _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list Sprinklerforum@firesprinkler.org http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum
