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RE: Flat Slab Bridge

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David,
Have you considered using a version of a vertical restrainer.  THese are commonly used in seismic areas and would allow an expansion movement.  You might have to thicken the abutment ends of your flat slab.  Properly designed you could then count on the dead load of your abutment.
 
LEE
-----Original Message-----
From: M. David Finley, P.E. [mailto:pec(--nospam--at)isgroup.net]
Sent: Tuesday, February 25, 2003 7:38 AM
To: seaint(--nospam--at)seaint.org
Subject: Flat Slab Bridge

I've got a project with several C.I.P. flat slab bridges with spans lengths of 13' / 30' / 13'.  With such short end spans, there is uplift at each end of the bridge if a continuous deck is used.  There is too much uplift to simply thicken the deck at the ends.
 
Rather than use simple spans to eliminate the uplift, I'm considering using integral abutments to resist the uplift.  I know integral abutments have been used sucessfully on steel bridges, but I've not heard of them being used on flat slab bridges.  A further complication is that the agency requires 24" sq. conc. piles.  Obviously, they will be much stiffer than the H-piles normally used in integral abutments.  I don't need a lot of movement in order to accomodate thermal expansion/contraction, but I do need some.
 
Any comments, ideas, suggestions?
 
M. David Finley, P.E.
2086 SW Main Boulevard - Suite 111
Lake City, FL  32025
386-752-6400