Being that Harold called me out:
Go to this link and then start
looking at the different joist figures starting on page 6 of the PDF:
If you find a figure that looks
like your joists return to Tables 1 & 2 of the article and cross reference
the Figure number to the joist description.
Let me know what type joist you
think you have and I’ll look and see if I have an available load table
and I’ll send you a copy.
From: Harold Sprague
Sent: Wednesday, April 14, 2010 1:25 PM
Subject: RE: Unusual Joist Designation
A gentleman, scholar, and list participant is D. Matthew Stuart.
Mr. Stuart wrote a series of articles in Structures Magazine on open web joists
in a series called Antiquated Structural Systems in 2009.
Back in the old days, joist designations would have the first 2 digits as the
joist depth and the following 2 digits would be a chord designation. But
I looked at what I had for Bethlehem joists and they did not track well with
what you have indicated for weights. Example: The 48L18 Bethlehem joists
weighed 61 pounds per foot. As opposed to the 52 pounds per foot that you
Regards, Harold Sprague
Date: Wed, 14 Apr 2010 11:09:55 -0400
Subject: Unusual Joist Designation
I am reviewing an existing building from 1955 with long span joist roof
framing. I am unfamiliar with the joist designations that were
used. They are:
#5620 - Wt 63#/LF
#5420 - Wt 63#/LF
#5219 - Wt 57#/LF
#5018 - Wt 52#/LF
#4818 - Wt 52#/LF
#4616 - Wt 45#/LF
#4215 - Wt 41#/LF
#3814 - Wt 36#/LF
The joists have clear spans ranging from 88 feet to 58 feet. I am
assuming that the first two digits of the designation are the depth of the
joist in inches. I am also assuming that the Wt is the weight of the
joist in question.
I would like to know the capacity of the joists to ascertain whether they are
strong enough to withstand the weight of a new roof that the architect wants to
add. Does anyone know where I could find load tables for joists with
these designations. Any help would be greatly appreciated.
Please respond directly to me as I am in digest mode.
Adam Vakiener, P.E.
Southern A & E, LLC
7951 Troon Circle
Austell, Georgia 30168
phone - (770) 819-7777, ext. 144
fax - (770) 819-7770
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