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Re: Neoprene Bearing Pads - Coefficient of Friction

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On 8/31/2010 8:01 AM, Jim Getaz wrote:
        Bill,
                The coefficient of friction between Neoprene and steel is higher than the shear deformation capacity of a properly designed bearing pad.
                Three Nelson studs will not secure the bearing plate in a double tee stem _if the bearing locks up_; a tail bar would required. ACI discusses this for corbels, Section 11.9.3.4 and the Commentary thereof. Due to equal and opposite reactions, the same force will develop in the tee stem. However, an adequate bearing pad relieves the forces by shear deformation.
        Regards,
        Jim Getaz
        Precast Concrete Engineer
 
Thanks Jim. In this case I'm talking about the bearing plate in the corbel (which in this case is actually a shelf in an L-beam). I will peruse the reference you give and make sure we're okay.

As far as the bearing pad is concerned, for bridges we see them "walk out" quite frequently. I'm sure there's more going on than just the shear - probably a "bouncing" effect - but that's just business as usual for bridges, I know from experience.