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RE: single plate shear connections

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Title: RE: single plate shear connections

>there is a lot of
>concern over whether or not you can weld a single
>shear plate to an HSS face or not but there doesn't
>seem to be the same concern when this type of plate is
>being welded to a wide flange column web.

The condition is similar, but the concern is more often expressed with HSS for two reasons:

1. A single plate is not a very buildable detail into the column web unless you change it so that it really isn't a single plate any more. Huh? What I mean is, a true singleplate witha 3 in. distance from the weld to the bolt line will often be well inside the flanges of the column if that connection were made to a column web. So it's hard to get in there to install the bolts, especially if they are specified as anything other than snug-tightened. You won't be able to get any kind of powered installation equipment in there to do it. Even worse, how do you get the beam in in the first place? You'd have to tip the column, which is a big OSHA erection no-no.

        When a single-plate-type detail is used into the column web, it most often built out with top and bottom plates so that the actual single-plate part of it extends out past the tips of the column flanges. But once you do that (and pay to do it too!), you don't have the same support concern anymore as would apply to a thin HSS wall.

2. If you do decide to use a single plate despite the concerns above (I'd think long and hard about it first), the range of wall thicknesses for HSS is generally limited to 5/8 in. or less (1/2 in. or less in many cases) with common wall thicknesses in the 1/4, 5/16 and 3/8 range. Column webs can be and often are thicker. The support concerns for single plate connections are not a problem once you get into thicker supporting element thicknesses. Also, there is usually a lot more stiffness in the column web due to the thicker flanges of W14's and the like than the "flanges" of HSS columns, which are of the same thickness as the face to which the connection is made.

Charlie