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RE: Concrete Tank Design Help

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Is the wall to slab connection at an interior wall or exterior wall? If at an exterior wall, is there exterior soil load which will put the exterior face in tension at the base of wall?
 
At interior walls, the wall dowels may use standard hooks into the base slab, assuming continuous reinforcement in the base slab.
 
At an exterior corner between a wall and base slab, and assuming moment transfer with tension at both faces, the outside vertical wall reinforcement should be lap spliced to the bottom slab reinforcement and the inside vertical wall reinforcement may be doweled with a standard hook. A standard hook at the outside of the corner does not provide adequate continuity if in tension. (At any plane cut thru the joint, you should have continuity of the outside tension reinforcement. If you just provide a standard hook on such a bar, you may get cracking in the joint due to partial restraint without adequate tension development.)
 
Also, the slab reinforcement must be able to resist the moment transferred from the wall.

William C. Sherman, PE
CDM, Denver, CO
Phone: 303-298-1311
Fax: 303-293-8236
email: shermanwc(--nospam--at)cdm.com

-----Original Message-----
From: Mark Seifried [mailto:mseifried(--nospam--at)ggjengineers.com]
Sent: Wednesday, September 25, 2002 8:29 AM
To: seaint(--nospam--at)seaint.org
Subject: Concrete Tank Design Help

My question deals with the transfer of moment from the base of a tank wall into the tank slab. I know that this connection can be assumed closer to pinned of fixed depending on the reinforcement detailing.

But, if this connection is assumed close to fixed, what kind of reinforcement is necessary to complete this transfer of moment into the slab? I typically see 90d standard hooks used as dowels at the same spacing as the vertical wall rebar… Is this tension development length provided by the hook adequate for transfer? Or does the standard hook EF result in more of a pinned connection since the length of rebar parallel with the bottom slab rebar is very small?

Thank you in advanced for your help or any direction you can provide?   
Mark Seifried, EIT