Large Base Plate Design for Axial Load

[gregeckel]

The fabricator on a job I am working on has requested larger base plates for constructability. I am wondering if I should make them also increase the base plate thickness. Using the standard method for determining the thickness of a base plate the thickness should increase. I've looked into other methods (like the murray method) but they all require that the base plate area be slightly larger than the column profile. It seems to me that for an only axially loaded plate the thickness should not need to increase (think about if you made the plate huge...the force will only bear on the concrete directly around the column profile)

Should I increase the thickness?

Thanks,
Greg

 

[oneintheeye]

i would think the effective area of the plate would remain the same?

 

[DaveAtkins]

If you design the plate "correctly," then, yes, the plate would need to be thicker. But if you use a thinner plate, the edges of the plate will deflect more, causing the bearing pressure to concentrate more under the column, allowing the thinner plate to work.

DaveAtkins

 

[csd72]

due to flexibility, only the inner areas of the plate will take all the load anyhow.

I would not increase the plate thickness.

 

[civilperson]

Check the bearing pressure on the concrete. Do not exceed the maximum allowed. This will set the plate thickness or add stiffeners to the column/plate connection.

 

[WillisV]

Agree with others - you can design the thickness of the base plate based on an assumed "effective" baseplate layout that meets concrete bearing requirements as long as you don't mind the outer portion yielding (which imho is ok in this situation).

 

[apsix]

I agree, no need to increase thickness unless there is tension and the hold down bolts are being spread further apart.