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Lateral restraint of steel beams at support locations

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I would like to get some opinions from those of you with structural steel
design experience.   AISC ASD B6 (Specifications Section) states that "At
points of support, beams, girders, and trusses shall be restrained against
rotation about their longitudinal axis."

Hypothetical situation:  A line of simple span WF roof girders is supported
vertically by interior TS columns.  At the support locations the
perpendicular beams do not occur directly at the columns, but approximately
4 feet away on either side of the columns.  The beams and girders are
supported on the top flanges by metal decking (no concrete fill).  The
connection of the girder to column is a standard bolted knife-plate through
a slot in the TS, or shear tab plate welded to the side of the TS column.  

1)  Could these girders be considered adequately restrained against rotation
at the columns by virtue of the connections?

2)  If a girder was a continuous or cantilevered member sitting on top of
the column, could you consider the beams 4 feet away as providing lateral
restraint against rotation at the column?

3)  If this line of girders is also a lateral load collector line, and one
of the girders is the top beam of a braced frame, could you consider the
column connections to be adequately braced against lateral displacement
under lateral loads?  

I realize that some of your answers may depend on the depths of the members
and/or the magnitude of the forces involved, but I'm not looking at one
specific project.  I'm trying to get a general feel.  

Also, I know some engineers who use a "rule of thumb" that lateral bracing
should be designed for 2 to 5% of the compression force.  Do many of you use
this?  I would like to get a feel about whether this is a generally accepted
practice. 

Karen Casano, P.E.
San Diego, CA

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