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RE: Flat Slab Bridge

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David,
 
24" P/S piles are pretty stiff to use in an integral abutment.  If you use this and generate uplift,
how will this affect stresses from your thermal movements? 
 
From your span lengths, I'm assuming that the 30' dimension is not negotiable.  Is there
any way that you can lengthen the end spans to get something like 20'-30'-20'? 
 
 
 
-----Original Message-----
From: M. David Finley, P.E. [mailto:pec(--nospam--at)isgroup.net]
Sent: Tuesday, February 25, 2003 9:38 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