Old Beam Size 20 I 56 1

[Mch2018]

I am working on an old building (maybe 30's or 40's?)and came across a beam labeled 20I56 and another 10I25.4. I have not been able to find section properties for these beams. Any help would be much appreciated!

 

[hokie66]

The 10" beam is here, on page 28. Not sure about the 20" beam, as all those listed are heavier. Have you checked SlideRuleEra's site?

https://www.aisc.org/globalassets/a...-data-pertaining-to-structural-steel-1940.pdf

 

[Ingenuity]

Maybe you transcribed the 5 & 6 and so maybe it should be 20I65?

 

[dhengr]

Mch2018:
There was a 20 I 65 (actually 20I65.4), and transposing 65 to 56 is a fairly common type of misprint. I would want to take some measurements on the beam in question.

 

[msquared48]

I agree with dhenger.

Nothing in the 1873 to 1952 summary or any of my other AISC manuals, 1949 to present.

Mike McCann, PE, SE (WA)

 

[Mch2018]

Thank you so much! Would these have been made from 20 KSI steel?

 

[LECT12]

It's a Bethlehem beam. Check AISC 1st edition, you can download them for free directly from AISC's website as long as you are a member. And it's probably 30ksi steel. Allowable tension was 18ksi during this time, 18/0.6 = 30.

 

[hokie66]

Two possibilities, but I'm betting on the 20I65.4. You should be able to determine which just by measuring the member in the field. The depth of all I beams in the same class remain constant, while the Bethlehem beams vary in depth with weight, like wide flange beams.

The best check will be just the width of the flange.