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steel beam bearing plate on concrete wall

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gte447f

Structural
Dec 1, 2008
706
Isn't there a code requirement that says something about the distance between the face of a concrete wall and the edge of a steel bearing plate on top of the wall? I seem to remember a minimum or maximum distance of about a half inch. Does this sound familiar to anyone else? I honestly can't remember if it is from the masonry or the concrete code.

My scenario is a steel beam on a bearing plate on top of a 6" thick concrete wall (beam is perpendicular to wall). The loads are small and the width of the bearing plate perpendicular to the wall is not critical for beam web crippling or concrete bearing, but I am inclined to make it as wide as possible anyway. Is there any reason not to make the plate same width as the wall (6")?
 
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Beyond the design aspect, you want to accommodate construction tolerances. providing a bit of wiggle room is always good.
 
Good advice on the wiggle room. Thanks.
 
Gte447f:
I like to leave the bearing pl. back from the edge of a conc. blk. or conc. wall for several reasons. This allows some distance from the edge of the stl. pl. to rake/finish any grout under it. Moreover, we know the beam will deflect, and tend to load the conc. on the very face/edge of the wall and you see the conc. spalling under the bearing when this happens. Finally, it looks like hell when the stl. pl. is hanging out over the face of the wall.
 
I prefer to make them the same width as the wall, that way they cannot misposition it in the form within the thickness of the wall.
 
OP said:
I seem to remember a minimum or maximum distance of about a half inch.

I may know where you've seen this. Someplace in the world of precast bearing design literature there is a recommendation for the bearing pads to be 1/2" back at a minimum. I consider this requirement to be more applicable to loads that are light and/or uniform than to your particular case (hollowcore etc).

Front loading and spalling the wall is an issue but I don't feel that the 1/2" business will save you either way. I think that you've either got to do some fancy detailing to shift the load application point back or you need to, as we usually do, hope to the powers that be that your beam stiffeners guide the load closer to where you want it. A nice stiff beam helps this situation too.
 
Thanks for all of the comments. I think I will go with a 5" plate in the 6" wall. What about the elevation of the plate? It seems that the plate should be elevated slightly above the concrete so that when the beam deflects it will not tend to crush or spall the corner of the concrete at the face of the wall if the plate is narrower than the wall and therefore may not extend to the face of the wall. Is it normal to elevate the bearing plate above the top of concrete or to set it at the same elevation?
 
1) Meh, I don't see that last half inch making much of a difference to anything if your general approach remains unchanged

2) In a post installed condition, usually I do see a grout bed and some vertical separation.

3) I've seen detailing in the past where there was, say, a 3/8" x 2" x 4" plate welded to the beam below it's stiffener in order to make sort of a poor man's "rocker" that delivered the load nearer to the center of the bearing plate.

4) If the wall has not yet been cast, I like a side connection to an embed for this.

5) As I mentioned above, I think that a stiffener pair and a stiff beam are your best friends here.
 
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