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Seated Beam Connections
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 Subject: Seated Beam Connections
 From: "John P. Riley" <jpriley485(nospamat)peoplepc.com>
 Date: Thu, 5 Apr 2001 23:29:28 0500
1. If it is an HCMU
wall, my preference is pockets with bearing plates (see SJI
specification 5.3(a)). I have a standard detail, want
it?
2. If you're asking what
allowable bending stress to use for the horizontal leg as a cantilevered beam,
my answer would be 0.75Fy.
3. I'd use e = 1/2 bf,
where e is the eccentricity of applied load relative to face of wall and bf is
width of horizontal angle leg. As the joist deflects and the
cantilever deflects, the effective e will move around, but I think it will
eventually be less than 1/2 bf. Of course, I'd detail the end of the
joist at about 1/4" clear of the wall.
4. Effective width of
cantilevered section . . . I'd use 6 or 8 inches, depending upon my mood.
This is engineering, not science. Do you know how wide the joist
bearing is? Must be about 5" for a Kseries joist. If the end of the
joist is sufficiently stiff to distribute the load 5", then 8" for the
cantilever seems OK to me.
5. After you do all your
number crunching, don't be shy about going thicker just for the heck of
it. My experience is that these things tend to appear appropriate
in details and breathtaking in the field. For what you've described,
my minimum angle would be L 4 x 4 x 3/8. The joist manufacture wants 4"
bearing (masonry), but will settle for 2 1/2" (steel). If you detail the
clearance between joist end and face of masonry at 1/4", it seems unlikely
that actual conditions will result in too much heartburn.
6. Just roughing this out,
without considering bending between anchorages (which I'd minimize by showing
the anchor bolts at the joists . . . because I don't think an angle is worth a
hoot in bending), assuming 55 psf roof load (30 psf
snow):
S = b
t^2 / 6 = (8)(3/8)^2 / 6 = 0.188 in^3
M = Fb S
= 0.75(36)(0.188) = 5.06 ink
P = M/e
= 5.06 / 2 = 2.53 k
P/5' = 2,530/5 = 506 plf
L/2 (max) = 506 plf / 55 psf = 9.2 ft
L max = 18.4 ft (max. joist span for 3/8" thick
horiz. leg)
L max = 25.1 ft (max. joist span for 7/16"
thick horiz. leg) L max = 32.7 ft (max. joist span for 1/2"
thick horiz. leg)
7. Hopefully, I did the
math right. If I did, then I'll say, "This is the easy part."
Do you have any questions about the anchorages? LOL
__________________ John P. Riley, PE, SE Riley Engineering 20 Oakwood Drive, Blue Grass, Iowa 52726 Tel & Fax: 3193813949 jpriley485(nospamat)peoplepc.com 
I would like some asistance to resolve a design
question. I am designing an angle used as a beam seat. I checked my
college steel book and Gaylord was using Fsubb = 0.66Fsuby. I checked some more
sources and Salmon and Johnson was using 0.75Fsuby, Fisher's Vulcraft book was
using 0.75Fsuby. Which one is right???
With a little more looking I found in the ASD Specs
F2.1 (Compact) Fsubb = 0.75Fsuby or F2.2 (Noncompact) Fsubb = 0.60Fsuby.
These sections refer to Section B5. Is the appropriate test b/t <
76/Sqrt(Fsuby)???
Finally, My real question, this angle is not a
single beam seat but a ledger angle supporting multiple purlins or bar
joists. What is the effective length of support to subsitute into fsubb =
(6*M)/(lsube*t^2)??? Surely it is not the 5' spacing of purlins, the 2'
spacing of bar joists, or the spacing of bolts or welds which attach the ledger
to the wall. How does one determine the effective length of support on a
continous ledger angle???
Thanks in Advanc
Jim Hannah, EIT
Butler Manufacturing
Company

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 Seated Beam Connections
 From: James Hannah
 Seated Beam Connections
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