Rectangular Concrete Tanks 2

[Mark10]

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?

 

[Ginger]

In the UK, to detail this connection as rigid we use 'L' bars from the wall passing into the base slab. The typical arrangement is: L-bar from outer wall face into top mat of slab, L-bar from inner wall face into bottom mat of slab, L-bar from outer face of wall to bottom mat of slab.

The use of hook bars is usually detailed for pinned joints.

 

[Qshake]

We use similar details here in the US for moment transfer.

Also please note that behavior of the connection may be confined to a local condition. For example, the fixed connection will reduce the moment effected in the wall from that of a pinned connection but will also act to reduce the moment in the slab which may or may not be desired. Large tank mats will not be influenced as much as small tanks and thus for the larger tanks the mat (for design) may be assumed as pinned at the wall.