Steel Bearing Plate

[RCSD]

Hi all

I am currently working on some projects however the designer prefers to use steel bearing plates rather then concrete padstones to rest steel beams onto

Does anyone have any experience in determining the depth of these plates?

I have found this online:

http://www.bgstructuralengineering.com/BGSCM13/BGSCM008/Design/BGSCM0080604.htm

However, this assumes a 100% load distribution through the steel plate regardless of depth and the depth is calculated from the plates elastic modulus.

I know there is an ASCE design method however I cannot get access to this.

Any help would be appreciated.

Thanks

 

[Agent666]

That method seems sound enough to me, though some regions of the plate loads would just directly transfer the load through the plate depending on what was on top of the plate and not create bending. For example the code bearing width for say a web/flange intersection at underside of beam mihgt just strut load directly though the plate, if the concrete under can take the load I don't think you need to consider anything further.

I'd typically consider the area of concrete in bearing that works, this will typically be the weakest link in the system and drive the plate size and thickness.

Then check cantilevered outstand of plate under the average load if you needed to spread the load further through the bearing plate than the typical steel on steel code bearing width (EDIT - I see the method you linked to actually already does this on a second look). I'd say the spread through the plate would be the same as the spread through a beam flange, usually 1:2.5 (or whatever AISC has in this regard, as not to familiar with AISC requirements).

I don't quite get why you are concerned about the assumption of 100% of the load through the plate? Isn't 100% of the load going through the plate in this scenario?

 

[RCSD]

Hi Agent,

Thanks for the reply, my confusion is with the spread through the plate. When designing concrete padstones I normally use a 45 deg spread. You mentioned a 1:2.5 (about 70 deg) spread but when I apply this same principle to determine the depth of a steel plate, the plates depth can become greater than that determined from the link. But the method linked suggests a spread of 100% no matter the depth.

 

[dauwerda]

In the link above, you start with the assumption that the load is spread over the entire plate, then the minimum thickness is determined to ensure that this assumption is true.