AISC changes W21x 55 vs W21x57

[PT999]

AISC Wide Flange Shapes
W21x55 is not in the 9th edition, but shows up in the 14th edition. How does that happen?
W21 x 57 are in both editions!

 

[jayrod12]

It makes sense that they would broaden their availability no? Maybe the W21x55 wasn't available at time of printing of the 9th edition?

 

[PT999]

Well to my knowledge, firstly most of the factory machinery has been set up some time ago, like 50 yrs or more, and is unchanged, and secondly, over the years shapes have been reduced for efficiency reasons. So I am wondering if it is a glitch?

 

[JedClampett]

It looks like they're from different families. The 55 has a 8.25 inch flange and the 57 has a 6.5 inch wide flange. If you look at the the way they adjust sections, they have a depth (21 inches in your case) and flange width and add to the flange thickness (and less so the web thickness) incrementally. That's why all W21's are not exactly 21 inches deep.

 

[PMR06]

You could ask AISC:

http://www.aisc.org/askaisc/default.aspx

I bet they would answer your question regarding the steel manuals, history of the shape, availability, rolling schedule, etc...

 

[BAretired]

According to my 2004 CISC Steel Handbook, one mill, TX1 Chaparral Steel announced that it has elected to suspend production of several shapes including W21 x 48 and 55.

BA

 

[wannabeSE]

To check availability, find producers at

https://www.aisc.org/steel/searchForm.aspx?id=2044