AISC Design Guide 2

[SpiderM]

I need help understanding an aspect of this guide. I have a W24x162 with a 6" diameter hole with the opening edge 4" from the bottom of the beam. The guide establishes ho = Do = 6" and ao = .4Do = 2.7". Now for my question...The parameter ∝ν must be <= 1.0. When calculating ∝ν, the result is less than 1.0. The guide does not explain why this would be the case or what bearing it has on the calculations. My confusion is this is a relatively small penetration, which is located more than 0.15d, why should there be any problem with these calculations?

 

[KootK]

They're just saying that the nominal shear capacity shouldn't be assumed to be any higher than the plastic shear capacity. It doen't indicate a failure or overstress. In your case, Vm = alpha_v x Vp.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[JoshPlumSE]

I'm no expert, but just going through the design guide again, I don't think it's possible for that value to be negative. Sorry, misread your less than 1.0 to be less than 0.0. Though the rest of my post remains valid (if a bit lazy).

Are you sure you're doing the calculation correctly?

I'd create an Excel or MathCAD spreadsheet for one of the example problems and make sure it matches the DG calculations. Then change it little by little to match my situation and see where it goes bad.... Sorry I couldn't offer any more insight than that.

 

[SpiderM]

In my situation ∝ = [(√6)+ 0.086]/[0.180+√3] = 1.33 > 1.0, then Vm=∝Vp ⇒ Vm>Vp which is not possible. So, do I limit Vm=Vp?

 

[KootK]

Exactly.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[SpiderM]

Thanks! I was pulling my hair out trying to confirm that conclusion.

 

[KootK]

You're welcome. Assuming that we're right in our conclusion, the guide really doesn't do a great job of communicating its intent.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.