AISC 2005 Chapter K Limits of Applicability

[volunteera]

AISC 2005 Chapter K is applicable to HSS only with Fy ≤ 52 ksi and Fy/Fu ≤ 0.8...In my case, I am welding a pad-eye to a round HSS which is a drill pipe with Fy=148 ksi & Fu=160 ksi which means both of the requirements are being violated.

On the other hand, the pad-eye is only taking 0.5Te transverse to the drill pipe which won't be a problem however I need to prove that on paper. Can these requirements still be conservatively applied though?

 

[JoshPlumSE]

My belief is that the code check and capacity equations in Chapter K are still valid from a theoretical basis. Two things though:
1) There may be other failure modes that need to be checked as well that aren't discussed in Chapter K.
2) The testing that validated those equations likely did not cover the range of materials that you have.

So, why the provisions can be applied I wouldn't necessarily say that they're inherently conservative.

 

[dhengr]

Volunteera:
As likely as not, the bigger problem with the drill pipe as the spreader beam will be a welding problem, weld quality, cracking potential, etc. etc. I’m sure you are using the drill pipe in this unusual way because it is readily available and generally works strength/stress wise. We don’t know the material properties or the metallurgical makeup of any of the materials you are using, but I suspect that the drill pipe is quite hard, heat treated and has a pretty high carbon equivalent number. Thus, it presents some welding problems, whatever the other materials in your design are. Then, we don’t know what your design looks like either, and a sketch would help on that account. I suspect you have a pad-eye above, the pipe spreader beam, and the lifting eyes below, with the loads going through the pipe btwn. the two eyes. I don’t have the last few Eds. of AISC, so I don’t know exactly what Chap. K says on the matter. Maybe a design change would help your cause. If you can do it, make the pad-eye (atop) and the lifting eye (below) in/on the same shaped end plate. Then, slot the pipe to fit around these end plates [t_slot = t_plate + 1/16"] so you get sufficient end weld length btwn. the plates and the pipe. These welds have to take some moment and the compression load in the pipe, but the primary loads are taken through the shaped end plates, a nice clean load path. You will still want to talk to a smart welding guy about preheat on the pipe, welding process and procedures, filler metal, etc.