TYPE OF OPEN WEB STEEL JOIST?
TYPE OF OPEN WEB STEEL JOIST?
(OP)
I am having difficulty identifying a joist which is at least 35 years old. Top chord consist of two channels (estimated at 1.5" deep by 1/4" thick). Bottom chord consists of two angles (leg size estimated at 1.5" by 1/4" thick). I have no engineering data and info on the type of joist. Current material on internet does not provide much help.






RE: TYPE OF OPEN WEB STEEL JOIST?
RE: TYPE OF OPEN WEB STEEL JOIST?
RE: TYPE OF OPEN WEB STEEL JOIST?
RE: TYPE OF OPEN WEB STEEL JOIST?
With my current assumption, the added loads are not significant to the roof support system, however I can not submit what I have to the buiding inspector until I can identify the type of joists.
RE: TYPE OF OPEN WEB STEEL JOIST?
Try to get a copy of the Steel Joist Digest, they have come out with the 75 year Digest 1928-2003 and covers all joists manufactured with specifications and load tables.
RE: TYPE OF OPEN WEB STEEL JOIST?
RE: TYPE OF OPEN WEB STEEL JOIST?
RE: TYPE OF OPEN WEB STEEL JOIST?
RE: TYPE OF OPEN WEB STEEL JOIST?
RE: TYPE OF OPEN WEB STEEL JOIST?
The older AISC steel manuals contain joist information including load tables and Fy's. Check the light blue manual - I think thats the Seventh Addition.
RE: TYPE OF OPEN WEB STEEL JOIST?
RE: TYPE OF OPEN WEB STEEL JOIST?
"Cumber": maybe the manufacturer's client; i.e., the general contractor who built the building? I like JedClampett's thought better.
RE: TYPE OF OPEN WEB STEEL JOIST?
Maybe if you call Vulcraft or another large joist supplier, they can tell you if they made 24J3's and what the capacity would be.
RE: TYPE OF OPEN WEB STEEL JOIST?
To rholder98: I am incline to believe that you are correct when indicating J3 does not indicate either an actual or nominal value for width of joist eventho this had been my impression. Publishers appear caggey about the design data of joist cross sections.
To apetr26542: Ca not answer your question because of lack of data on J series; however these are my values:
uniform load : 81 lbs/lf
point loads : 379 lbs at x=26'
190 lbs at x=33'
reactions : 2185 lbs at x=4'
1950 lbs at x=44'
Overhang : -324 lbs resisting shear at x=4'
-648 ft-lbs resit. moment at x=4'
average shear stresses: 1537 psi at x=4'(A=1.42 in^2)
1248 psi at x=7.83'(XA=1.24)
Truss Analysis @x=26' where bending moment is max
at +20,637 ft-lbs
Sc=15,400psi thru centroid of top chord
St=20,324psi thru centroid of bottom chord
Rc=341 lbs thru 3/4 dia diagonal
Based on yield strength of 22,000psi I am about 5% lower in my resultant stress for the lower chord which is too close for comfort--What do you think?
RE: TYPE OF OPEN WEB STEEL JOIST?
RE: TYPE OF OPEN WEB STEEL JOIST?
Chicopee, if you are under the allowable stresses, would think you are ok, for a 24J6 which is the smallest published for a 24" joist the allowable moment is 30.5k-ft, this is based on load tables published in 1971. However, since you are adding point loads, you may be overstressing certain web members, can you construct the allowable shear diagram, also these point loads should be added at a panel point or a reinforcing web angle added.
RE: TYPE OF OPEN WEB STEEL JOIST?