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Steel Moment Frame - Channel to TS Colum

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Mark,

I am HERE!

If the channel is welded to the face of the TS (HSS) it would be, IMO, a 
partially restrained connection, no matter how you welded it.  The face of 
the tube is thin in comparison to the stiffness of the channel and will 
deform ("oil can" in at the bottom, out at the top for -M), providing 
rotation at the connection.  I try to avoid connections to the face of a tube 
like the plague.

I would probably weld some plates to the sides of the tube, connect these top 
and bottom with cross plates and then weld the channel section to these cross 
plates.

Hope this helps.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

Mark Swingle wrote:

(Pleas edited out)

>>Please consider the following examples.  These are beam-column
moment connections, all of which consist of a channel section
as the beam, and a TS as the column (1/4" thickness).  All are
welded connections with no stiffener plates or continuity plates
at the column.

I am trying to determine whether each of the following
connections are judged to be FR (fully restrained) or PR
(partially restrained).

1.  An A36 channel, narrower than the TS, welded with CP groove
    welds at both flanges, and fillet weld (one or both sides)
    at the web.

2.  Same as 1., except the flange welds are fillet welds both sides.

3.  Same as 1., except the flange welds are fillet welds one side.

-------------------------------------------------

4.  An A570 Gr 45 channel, 10 gage (with stiffened flange), same
    width as the TS, welded with CP groove welds at both flanges,
    and a flare bevel groove weld at the web.

5.  Same as 4., except the flange welds are fillet welds both sides.

6.  Same as 4., except the flange welds are fillet welds one side.

-------------------------------------------------

7.  Similar to 4., except the flanges are coped and the web
    continues to the far side of the column.  The web "extension"
    is welded horizontally to the column (T&B) with fillet welds,
    and the web is welded vertically to the column at the inside
    corner with a flare bevel groove weld.

8.  Same as 7, except with flange welds per 5.

9.  Same as 7, except with flange welds per 6.

-------------------------------------------------

Per UBC 2213.6 (OMF Requirements) the determination of whether
these connections are judged to be FR or PR is critical to the
analysis.

If they are judged to be FR, then they may be designed by
calculation only with an omega factor on the typical design
forces (2213.6 Item 2).

If they are judged to be PR, then they must be TESTED to
determine the inelastic rotation capacity (2213.6 Item 3.2),
in addition to other design criteria.

Any comments would be appreciated, including whether CP groove
welds are possible on A570 10 gage material.

Mark Swingle, SE
Oakland, CA<<