AISCM 15th edition 7

[LeonhardEuler]

I recently purchased a new AISC Steel Manual and upon using table 3-10, for LTB stength of Gr.50 I-beams I have noticed that they reduced the table to only include beams stronger than 300 kip-ft the old manual extended much farther. Does anyone know why this change was made? This was an extremely useful table, has there been research done to suggest that the beams weaker than 300 kip-ft should not be used, or something of this nature?

 

[dhengr]

LeonhardEuler:
The steel suppliers and the steel mills started charging extra for the extra LTB in the lighter beam sections. So, in retaliation the AISC stopped showing them in their tables…, I think. The continuous casting process does not allow the continuous bloom to solidify and cool sufficiently for the LTB to be properly redistributed in the final section when it is being rolled, too much of it gets squeezed out during the rolling of the lighter sections. And, during the melting process they just have to put too much extra LTB in the ladle, so they quit doing it. A good deal of that squeezed out LTB ends up on the mill floor in the form of mill scale, and they are working on a process to refine it back out of the mill scale so they can put it back in the ladle in a cleaner form. Now, AISC is trying to get back into the picture too, they are trying to gain all the rights to the LTB. They plan on selling it in liquid form. They will completely eliminate table 3-10 and just allow the engineers, fabricators and contractors to sprinkle some on their beams, as needed. Kinda like holy water, yuh know.

 

[TehMightyEngineer]

What?! That saves them like 7 pages! Those were the most useful pages in the manual apart from the connections. To say nothing of practical design work; those pages in Table 3-10 were a godsend on the SE exam. I thought it was bad enough they didn't include the W6 sections in Table 3-10 in the 13th edition.

If they wanted to save space they should have cut out some of Table 3-8. I almost never use that one.

Ian Riley, PE, SE
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[TehMightyEngineer]

Oh, I know why; it's because they added the new "super tables" into the manual. I still haven't used these in practice but in theory it should replace the functions of Table 3-10. I guess I can forgive them if I can at least get the information elsewhere. Plus the part 6 super tables go down to the smaller W6 and W8 sections, unlike the 13th and 14th edition table 3-10.

Ian Riley, PE, SE
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[JoelTXCive]

I wish that AISC (or somebody) would make a poster size Table 3-10 that we could put on the wall...

 

[271828]

I'm a little confused. My Table 3-10 includes flexural strengths much lower than 300 kip-ft. On Page 3-127, I see a W8x10 going out to 18.5 ft with a phiMn of about 7 kip-ft.

 

[LeonhardEuler]

Update, after scaring people with the threat of fewer tables. My brand new manual is missing 33 pages. The rest of table 3-10 is likely in those missing pages.

Good to know about the extra price for LTB though, I will make sure to design LTB's out of my structure before ordering in the future. If I can prove to the mill that all beams are adequately braced do you think I would get a discount? They would surely save alot on LTB ore, difficult mining process. I hear that the price of torsional warping transducters may actually be on the rise as well. Good things to look out for.