Old WT sectional callout 1

[driftLimiter]

Working with some existing (really existing, circa 1950) truss I see this callout for what looks like a WT section.

ST 4 JR 3.25

I am trying to pull historical section properties and I'm not seeing anything like that in AISC DG 15. I've tried some other historical references as well with no luck.

Based on the detail, and intuition of WT shapes. I think its pretty safe to assume that the section is cut down from an 8" beam weight 6.5 #/ft.

I showed some collegues and they just laughed and said "Junior Beam huh?" Then proceeded to tell me that its probably cut from an 8" beam that weights 6.5 #/ft.

1.) What does the JR reference mean here? I saw a few of these callouts in historical references but no clear definition.

2.) Should I be looking for S-Rail shapes as well as WF shapes?

3.) Anyone seen a historical WT that matches these properties or even an I beam?

 

[phamENG]

I seem to recall references to "junior beams" in one of the old Bethlehem manuals. I'll see if I can find it...

Yes, you should be looking at S-shapes here if they're calling out ST's.

 

[phamENG]

Junior beams, in case you want to order one today...8"x6.5# is listed.

 

[phamENG]

Here's a page from the 1926 Carnegie manual. Shows a T-1 with a 4" stem (ST 4?) and a weight of 10.5plf (pretty close to your 10plf). Could be a variation between years. How old is the structure?1950, I got it.

 

[phamENG]

Here are your 1950 junior beams (AISC SCM, 5th Edition)

 

[phamENG]

Looks like the same manual also gives properties for the junior ST. Nothing for the 5plf beam. Probably a WF for that - they have the 10plf 8" beam listed under "joists".

 

[driftLimiter]

Thanks @phamENG I'm only left curious what the S part of the callout means. These guys called out other wideflanges like this 6B12 I eventually was able to figure that one out also.

 

[driftLimiter]

@phamENG the other callout is right there on the same page. ST 4 B 5.

And I guess ST means structural Tee not cut from an S shape

 

[JStephen]

In one of my references, they had T's listed that were not cut from beams, apparently just rolled like angles. I think they were listed along with the the rail-car sections and whatnot.
I don't know about the junior beams, but I recall my former boss saying they used to have some special sections (taller, thinner I think) that were specifically for the mobile home industry.

 

[dik]

from the W8x6.5 noted above...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[phamENG]

Ha. So it is. Good eye. And you are correct, Structural tee is the designation.

 

[straub46]

I feel like I remember looking into this and discovering that the JR beams basically became the M beams AISC uses in Table 1-2. The old designations were weird.

Go Bucks!