Single Plate Connection to Column Web - Eccentricity of bolts 1

[matrixeric]

hello All:

I had always assumed that a single plate connection to column web (with a> 3.5") is an "extended configuration" per AISC as the bolt line is typically more than the AISC stipulated value of 3 1/2" and one cannot ignore eccentricity when considering the bolt strength.

However, when I use DESCON software to design a moment connection to column web the bolts strength is being arrived at by assuming that there exists NO eccentricity even if the "a" dimension is greater than 3.5". Does the fact that the shear tab being welded to the plate stiffeners of the column have something to do with this or am I doing something wrong?

Appreciate your input!
Thanks.

 

[connectegr]

The determining factor in your example is the moment connected beam. The flange welded or flange bolted connection eliminates the eccentricity in the extended shear plate and beam web bolts.

For non-moment connected beams there have been many discussions related to the appropriate eccentricity to be considered in the bolts. The AISC design examples and most software applications, consider eccentricity to the weld line. This is regardless of whether stiffener plates are provided.

Arguments can be made for taking eccentricity to the toes of the column, or the nuetral axis of the "C" weld group. Depending on the loading, these options may induce moment in the column, that should be considered in the column design.

PS The rules for eccentricity in single plate connections (shear tab) have changed again in the 14th Edition manual.

http://www.FerrellEngineering.com

Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.

 

[dik]

There are some excellent examples, here:

http://project.access-steel.com/Content/Content.htm

You have to register, but no cost or hiccups...

Dik