WF to HSS Connection - Chapter K of AISC 13th Edition 1

[bookowski]

I am looking at a WF to HSS moment connection. To get the capacity that I need I will need either the diaphragm through plate, cut out, or stiffened T type connection. I am not clear on how N is measured (in chapter K of 13th Edition AISC). It is stated at the bearing length parallel to the HSS axis.... isn't the HSS column axis vertical? If so then what length am I measuring. Design Guide 24 does not have any examples of this type and chapter K does not offer any illustrations. Does anyone know of any examples or diagrams to clarify how N is measured (as well as H).

 

[bookowski]

Might have answered my own question but would appreciate confirmation. N is measured vertically (in the case of a column at least). So for a cut plate wrapping the column, it would be the weld size (if it's welded on one side only). If I used the WT type connection (as shown in AISC) N would be the height of the T, which is bf (or the weld length along bf). That sound right?

 

[wannabeSE]

I don't understand your connection detail. A sketch would be helpful. However, the commentary for chapter K has illustrations showing "N" that may be helpful.

 

[racookpe1978]

Not clear what you meant by "a cut plate wrapping the column" ....

 

[bookowski]

The cut plate type is described on page 12-22 with a diagram on 12-23, the WT type is described on page 12-26 with diagrams on the same page. I think I figured out my question - but if anyone has any resources for examples or further explanation that would be helpful. The 13th edition and the design guide for HSS are both lacking in examples and clarity for these types of connections.

 

[bookowski]

Not getting a lot of takers on this one...

I am still not clear on chapter K. If I am using a diaphragm plate or a cut plate as shown on 12-22 I would have a Beta > 1.0 (Beta = width of plate/width of column). The checks that I see in chapter K are for Beta < 0.85 and Beta = 1.0... I don't see anything for Beta > 1.0. If the plate is wider than the column as in the cut out connection is Beta assumed to be 1.0?

I have a one sided moment connection so I can not continue the diaphragm plate to another beam.

 

[bookowski]

I emailed AISC with this question, I figured I'd post the answer just in case anyone else runs into the same situation. It appears that AISC doesn't have any explicit guidelines for designing one sided diaphragm plate connections through an HSS column. They advised me to follow first principles and design each component for appropriate demand/capacity - flange plates, welds of flange plates to side walls, shear in side walls, panel zone, etc. etc. So in general the guidelines set forth in chapter K don't explicitly apply to this connection type, although some of the pieces may be applicable. I was surprised that then didn't have more input on this since it is a recommended configuration that is shown by them in the Moment connection chapter of the 13th Edition.