Old time steel shape 21 B 49

[StrP88]

I am trying to get information on this steel shape , "21 B 49"
I dont know where to find some info on it? Such as Fy?
Is it unconservative for section capacity just use 21 W 49? What is potential risk?
Anybody can give me moment capacity of the beam for different lateral supports like we have it for 21 W 49 in AISC 9th Edition

Thank you

 

[SlideRuleEra]

Can you define "old time" more closely? The date will affect the answers to your questions. The decade should be good enough (e.g. 1950's).

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[boo1]

AISC Design Guide No. 15, Chap. 4, Enhancement of Existing Structural Systems provides practical data for renovation; Appendix A1, Historical Review of AISC Specifications –1923 to 1999

 

[Guastavino]

I would guess the Fy=36ksi, but depends on timeframe. I have an AISC 6th edition manual that has the 21B49 in it (t was called a "light beam"). Here are a few properties of it:

Ix=970.3in^4
Sx=93.2in^3
Depth=20.82"
bf=6.52"
tf=0.532"
tw=0.368"

I'd recommend going to amazon and buying a copy of the 6th edition manual. Likely cheap.

 

[StrP88]

njlutzwe (Structural),
Thank you very much for the sectional properties.
Why guessing 36 ksi ? Isn't Fy stated in that code?

SlideRuleEra (Structural),
DWGs are dated 72

boo1 (Mechanical),
Thank you for trying to help. What information I would find there?

 

[JedClampett]

To answer one of your questions, in 1972 there were several grades of steel available. It's not stated in the code (which one is used, just how to design with each type), it was the project designers choice. But you'd be safe using A36. That was by far the most commonly used steel.

 

[Lomarandil]

Agreed, A36 is probably safe for the 1970s. (AASHTO's MBE concurs, if you need a reference).

It's generally treated as a conservative steel to assume if the grade is unknown, but I've seen steel from the 20s and 30s that wouldn't have met A36 (either made to A7 or the designer wrote his own spec).

 

[StrP88]

Is there any test or method to figure out the Fy for an unkown structural steel member?

 

[jayrod12]

take a coupon and get it tested.

 

[BAretired]

Testing a coupon is not recommended. That is what was done in the case of the Station Square Save On Food store in Burnaby, B.C. The coupon tested high but as I recall it was taken from the web and overestimated the strength of the beam which collapsed on opening day. Admittedly, there were several other factors which played a roll in the collapse.

A36 is probably the steel specification which was used in 1972.

BA

 

[msquared48]

I would suspect A-7 steel at 33 ksi in that vintage.

Mike McCann, PE, SE (WA)

 

[hokie66]

In 1972 in the eastern part of the US, pretty much everything was A36. I remember when Bethlehem, or it could have been US Steel, brought out those light beam shapes, and they were A36 at that time. Later, maybe 50 ksi.

 

[3Fan]

I agree on the A36. Attached is a clip from our DOT load rating manual on material property assumptions if the grade is unknown. I would imagine they are fairly conservative in their range of years.

 

[boo1]

AISC Design Guide No. 15 has data on typical steels and strength

 

[Hokie93]

njlutzwe: can you tell me the page number in the 6th edition AISC Steel Construction Manual on which you found the 21B49 properties? I don't see it in my copy of the 6th edition manual. My copy of the manual is the first printing (1964). Do you have a later printing? The "light beams" in my 6th edition AISC Steel Construction Manual stop at 16" deep (31 pounds per foot).

 

[msquared48]

I do not see it in my copy of the 1873 to 1952 AISC shapes either...

Nor in my 1956 AISC Design Manual. All the sections listed there are WF sections

It is interesting to note on page 202 of that same manual that 20,000 psi is the limiting stress here for the beam span tables, implying 33 ksi steel (.6 X 33 = 19.8).

My 1967 copyrighted edition of the 6th edition shows no such beam either (first copyright 1963). 21 WF sections start at 55#/ft and there are no B sections shown above 16" deep.

The beam span tables in the 1967 copyright of the 6th edition were designed for A36 steel.

I am wondering if this was a non-standard beam not shown in the tables. If so, testing would really be required for the Fy unless you assume 33 ksi to be conservative, depending on the year of construction.

Mike McCann, PE, SE (WA)

 

[hokie66]

These shapes came out in the early 1970's, from either Bethlehem or US Steel. There was a brochure which went out to consultants at that time. I don't seem to have my copy anymore.

 

[Hokie93]

That would be consistent with the W21x49 being included in the 7th edition AISC Steel Construction Manual, my copy of which is dated 1973 (first revised printing). Interestingly enough, that was the only AISC manual that included the W21x49.

 

[msquared48]

1972 drawings - A36 then.

Mike McCann, PE, SE (WA)

 

[wannabeSE]

This is somewhat related. AISC members can download PDFs of the 1st thru 7th edition Steel Construction Manual at

https://www.aisc.org/content.aspx?id=40044