Steel Column Cap Plate Design

[PEinVA]

I have a W section column which has a W section beam pass over top and rest on the top of the column. Is the cap plate design to be treated as a base plate design if I don't have stiffeners and if I have stiffeners is it more for constructability?

Thanks!



RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke

 

[Lion06]

stiffeners on the beam? It is always good practice to provide beam stiffeners over columns and other supports (including other beams). This is a support point and is required to be restrained against rotation.

 

[PEinVA]

SEIT,
I agree about the stiffeners, but the main question I'm asking is about the cap plate. Is the cap plate just a matter of ease of construction for the contractor to have something to bolt the beam to during erection?

Thanks again.

RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke

 

[Lion06]

No, it's not just a matter of ease of construction. The stiffeners prevent rotation, by bolting the beam flange through the cap plate. If the beam is not positively attached to the column in some fasion then the stiffeners wouldn't help. Without the cap plate you would need to field weld the beam to the top of the column. Additionally, if the web of the beam is parallel to the web of the column then you need the cap plate to give the stiffeners something to bear against as they work to prevent rotation of the section (assuming you center the stiffeners over the column).

 

[PEinVA]

SEIT,
Again, thanks for the response, but maybe I'm just not being clear enough. My stiffeners line up with my column flanges, so they potentially (within tolerances) are going to bear on the flanges. Like you state the cap plate is there to attach the beam to the column. With the described condition the size of the cap plate is a matter of preference over design correct?

Thanks again.


RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke

 

[WillisV]

Yes. If bearing strength of the column flange steel is adequate then technically you can just plop the beam right down on top of it and field weld it as StructuralEIT said. The use of an actual cap plate is more of a ease of constructability concern.

 

[DaveAtkins]

I think you may be wondering about bending in the cap plate. Since you have provided stiffeners above the flanges, there will none. If you had not done this, the load from the beam web would have caused bending in the cap plate.

DaveAtkins

 

[hokie66]

Dave,

I don't think you would get bending in a cap plate from the beam web. Certainly not with the beam web and the column web colinear, but even in the opposite direction, the beam would be so much stiffer than the cap plate that the cap plate wouldn't see much load.

For uplift forces, the cap plate would bend because the force would transfer through the bolts.