BL Steel Section?

[LicensedToPEe]

I'm working on a rehab project (medium sized stadium) that was build around 1966 and some of the framing refers to a BL steel section (such as 18BL35). Now, from the 6th edition of AISC code, I see there are B sections (light beams) but they stop at 16x5-1/2B. From the details, the BL section has a shape of a WF section but I can't figure out what the difference would be. In my situation, I have a5 span girder made of 18WF50's that has 18BL35's as its 2nd and 4th spans.

Thanks for any help...

 

[MWPC]

My old steel beams book shows Bethlem using the BL for light beams as late as 1948 and the book only goes to 1952. Hope this helps.

 

[msquared48]

The AISC publication, "Iron and Steel Beams 1873 to 1952" shows "B" beams 15" and 16", BOTH AT 35 #/FT ON PAGES 63 AND 66.

Nothing in the Fifth edition of the AISC manual (1956) either.

Sorry for the caps.

Mike McCann
McCann Engineering