For new members, AISC 360-05 table 2-3 (page 2-39) has steel types and shows which steel is the preferred material specification. Of course, if this is an existing member that may not be appropriate depending on the vintage.
What's interesting, is that, in my quick research for availability, the general contractor sent a "CERTIFIED MILL TEST REPORT" for (2) specific S12x40.8 that are available from NUCOR-YAMATO. The Yield Strengths are certified at 56ksi for one piece and 59 for the other.
While AISC Table 2-3 states the "Preferred Material Specification" is Fy=36 ksi, does it seem reasonable to design and specify the beam at 50 ksi? Why wouldn't i?
Do you guys actually see 36ksi material in the US? I rarely see it in Canada anymore except on really thick plates. Anything rated to A36 is usually dual rated to something much higher as well.
Plate at 300MPa is generally the common structural callout for plate in Canada now, but mill reports I've seen from them are generally quite higher than spec by a reasonable amount. We used to call out 260MPa just to be sure of supply, but I haven't seen anyone bother in years.
For shapes, almost everything is 350MPa except for a couple of 300MPa holdout shapes.
BSVBD:
If you don’t have the general concept and understanding that you, as the engineer, should know, spec. an ASTM std. material or determine the grade and/or Fy by testing, for the beams you are designing; isn’t there some question about whether you should be doing this kind of structural design? AISC does not tell you that.
We used mill certs. all the time, with almost all of our material. We had a very good paperwork and records system and when needed we could relate a piece of material to a supplier and a heat number. That is, as best and reliably as this can be done. I always looked at the mill certs. on particularly significant pieces of materials. In our designs we generally used the ASTM values for mechanical properties. But, there were some times when I needed a few more ksi in terms of Fy or Fu, that I would use a significantly better Fy or Fu from the mill certs. to justify that exception of using the higher values. I worked for a special design and build division of a steel fabricator, so I had direct access to the mill certs. The run-of-the-mill Structural Engineer usually has a bit more trouble tracking specific pieces of material and getting their hands on the mill certs, since they design the job, knowing nothing about the G.C. or the fabricator at the time of the design. Thus, they call out an ASTM std. in their design specs., and their supplier/fabricator are expected to meet that.
