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Column Web Shear Strength - Neglecting Beam Flange Forces?

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Ben29

Structural
Aug 7, 2014
326
I am the SEOR and I am checking the steel connection design calcs. The calculation software (Descon) calculated the required column web shear strength to be ~ 600 kips.
The engineer that did the calculations did an override in the DESCON system to say that the required shear strength = 0 kips. I think he did this so he didn't have to use doubler plates. See page 3 of the attached calc.

I am not sure why or how this is allowed. Can someone explain this to me? I read AISC Design Guide 13 (section 4.1.1 Panel-Zone Web Shear). It specifically states, "When the column web thickness is inadequate to resist the required panel-zone shear strength, a web doubler plate is required. Alternatively, diagonal stiffening can be used if it does not interfere with the weak-axis framing."
 
 https://files.engineering.com/getfile.aspx?folder=c7e9b9dd-8f78-40d8-83ae-fee1606f3f5d&file=_Connection_Design_(MC-30).pdf
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I don't know why the designer decided to override the program. He shouldn't do it without explanation.

Are the moments have same sign (rotate in the same direction)? If so, you are correct, a web doubler plate is required. Otherwise, this check does not make sense.
 
I haven't worked with DESCON at this level of detail for awhile but I recall program was very conservative in calculating web doubler plates since it doesn't consider the sign of the moment.

BTW, he also overrode the flange weld check of base metal strength, not an unreasonable choice given the alternatives but just to mark it as CJP so no base metal checks is a little fishy.
 
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