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Eccentricity with Knife-Plate?

Eccentricity with Knife-Plate?

Eccentricity with Knife-Plate?

(OP)
If you weld a shear tab to (1) face of an HSS steel column, to support a beam with a single shear, bolted connection, you impose an eccentric load on the column.

If you specify a knife-plate, or through-plate shear tab that penetrates (2) opposing HSS faces and is welded to the same (2) faces, if the depth of the through-column shear tab would be equal to the length of the shear tab, would the eccentricity go away?

RE: Eccentricity with Knife-Plate?

The eccentricity must be accounted for somewhere. If you are assuming the column is concentrically loaded, then the line of bolts which connects the beam to the shear plate must be designed for the eccentricity between the center of the column and the line of bolts.

DaveAtkins

RE: Eccentricity with Knife-Plate?

The through plate would not make the eccentricity go away. It would only improve the connection mechanically by allowing the moment to be transferred to the column via axial forces in the side walls rather than side wall distortion. I don't recommend the through plate connection. It's costly and usually unnecessary.

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.

RE: Eccentricity with Knife-Plate?

In AISC code, eccentricity (with respect to the column and plate) can be ignored if the single plate connection is not an "extended configuration". Too long of a knife plate or multiple rows of bolts will cause it to be "extended", regardless of through plating or not. The purpose of through-plating is to avoid web plastification or rupture at the weld line. Many engineers show this connection until someone complains.

"It is imperative Cunth doesn't get his hands on those codes."

RE: Eccentricity with Knife-Plate?

Came here to say what MacGruber posted. AISC allows you to consider it non-eccentric if you follow their prescriptive details.

Maine Professional and Structural Engineer
American Concrete Industries
www.americanconcrete.com

RE: Eccentricity with Knife-Plate?

TME/Mac: can either of you point me to an AISC clause? I wan't aware of this but I'm glad to hear if it.

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.

RE: Eccentricity with Knife-Plate?

It is actually not in the code.

See Part 10-102 of the manual. It is just one of many handy simplifications you get when you shell out $1,000,000 for the manual (specs are free).

"It is imperative Cunth doesn't get his hands on those codes."

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