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Existing Bridge--Steel girders cast directly into concrete piers and abutments

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Have you looked into the concept of surrounding concrete providing a
confining effect on the concrete under bearing stress.  The AISC base plate
design guide includes a provision for adjusting up allowable bearing
stresses when the area of concrete under the baseplate is surrounded by
additional concrete.

Stan Johnson

> The steel beams bear directly on the concrete at the piers and =
> abutments; indeed they are embedded into them an unknown distance.  My =
>"old" reference (1924 Structural Engineers Handbook, by Ketchum, McGraw =
> Hill) gives an allowable bearing of 600 psi on concrete.  This seems =
> reasonable to me for the existing materials.   If I assume (and then =
> verify) that the beams are embedded fully through the piers, and the =
> full width of the bottom flange is effective in spreading out the beam =
> load (which it is not because of longitudinal flange bending) I still do
=
> not have enough bearing area for dead plus live loads. =20