Correct, that is a good explanation. Unistrut is not much good for 5' to 7' spans of 3" or 4" or larger sprinkler pipe. Hence my previous assertation that its use as a trapeze is limited. It is too often used where not appropriate. This subject is done now, thanks.
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Monday, July 23, 2007 11:47 AM To: [email protected] Subject: Re: Section moduli of Unistrut Section modulus is an engineering formula which provides a property (measurement) of a cross sectional shape and reflects both the shape and orientation of the object. It can be determined through the equation S = I/c, where I = moment of inertia about an axis through the centroid, and c = distance from the centroid to the extreme edge of the section. This is according to the "Manual for Steel Construction, 8th Edition" sitting on my bookshelf. This volume also has page after page of various S values for dozens of shapes in dozens of sizes, including both slotted and non-slotted channel, S members, I, members, W, members, C-channel, etc. And NFPA-13 ('02) would certainly allow you to use trap members other than those shown in the standard, as long as they had the appropriate section modulus. Section 9.1.1.6.2 advises "Any other sizes or shapes giving equal or greater section modulus shall be acceptable" which seems pretty final to me. And I don't know about Unistrut not working for trapeze members. Base don the values shown as a minimum in NFPA-13, I could use a 0.202 section modulus uni-strut to create a 3'-0" span trapeze to support 2-1/2" schedule 40. PARSLEY CONSULTING Ken Wagoner, SET 760.745.6181 voice 760.745.0537 fax [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> e-mail www.ParsleyConsulting.com <http://www.ParsleyConsulting.com> website _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
