AISC Manual (13th Ed.) Table 3-6, Max. Total Uniform Load

[palves]

Does anybody out there use this table? I decided to check it out recently, but it doesn't seem to be very user friendly. A few questions.

-Why do they bill it as a "Uniform" load table when they give it to you in kips? Assuming it means kips/foot will give you a moment far higher than the allowable.

-What exactly is the Wc (Uniform load constant) and why is it in k-ft? I've never seen this variable before.

If there is some insight out there I'd love to hear it. Thanks.

 

[TLHS]

Don't have the AISC handbook in front of me, but assuming it's the same concept as the CISC tables then it's expressing the total applied load (i.e. [load/unit length] x span ).

So if you see 100kN as the load at a span of 2m it's a total load of 100kN spread uniformly over 2m or 50kN/m across the whole beam. I'm betting there's a series of diagrams in there somewhere that tell you what the equivalent tabular load is for a variety of different load conditions.

 

[SteelPE]

I find every engineer uses these tables in one form or another.

Recently I have been asked by fabricators to design connections for given project and every send of engineering drawings references using 1/2 UDL to design connections on beams where the load is not given at the end of the beam. It's frustrating to have a 3' long W12x14 that has a UDL of 85.6k meaning I need to design the connection to resist 42.8 kips.

All the answers to the questions you are asking can be found on page 3-27.

 

[RWW0002]

Beware that the notes concerning Wc on page 3-27 in AISC_13 are not correct. Errata from Feb 3, 2009 states:

The 4th paragraph should read, “The uniform load constant, φbWc or Wc/Ω (kip-ft),
divided by the span length, L (ft), provides the maximum total uniform load (kips) for a
braced simple-span beam bent about the strong axis.”