Load transfer from beam to column flanges in shear connection 2

[IJR]

A friend of mine had this fear that a steel beam simply connected by a seat kind of connection, to a column flange of a WF would overload only that column flange.

So to be on the safe side he elected to add a thick plate to that column flange from floor level to base.

Is this fear justified?. Wont load eventually be transmitted to the whole section of the WF?. In my experience with connections loads usually propagate around 30 to 45 degrees outwards from the line of action.

In engineering world we always have these worries, and my observation is that when one is worried and there happens to be no established data around for use, the worry propagates to others as well until stopped.

So any explanation is highly appreciated.

Respects

IJR

 

[Ron]

IJR...I would not be concerned with this condition as the line of force is straight down the flange, assuming no bending is introduced. If bending is introduced, this is handled by the interactive equation of combined loading.

I realize the seat introduces some small eccentricity to the flange, but it is truly small and in most cases negligible. Keep in mind, the seat does not take all the shear load, only a part of it. Assuming a properly bolted connection (friction criteria, proper holes, torqued bolts, etc.)then the flange loading is truly linear, with the seat as only a convenience. The same would apply to a welded connection.

Further, in any of these connections you will actually introduce and resist some rotation of the joint (moment). This is inevitable, but in analysis, it is handled by the assumption of connection type. Depending upon the criticality of the connection, you can apply partial moments if necessary to more accurately assess the stress distribution in the columns. The relative stiffness of the column will come into play in all of this.

Ron

 

[IJR]

Thanks Ron and respects as usual

I understand that even if shear acts on one flange, the load will eventually be transmitted to the other flange by eccentricity action, I mean the familiar simple bending stresses will occure on both flanges with the flange next to the beam taking compression not from the full beam shear but from beam shear induced eccentricity Vbeam * h/2 where h is the depth of the WF

That does explain it all. You are working late. If in US then you should be asleep this hour.

Respects
IJR