Development Length for Concrete Wall With Uplift

[Struct2468]

I'm a little confused on when development length applies. I understand development length is used to transfer the tension and compression for the rebar in a beam to a column joint. Can tension development length be used to transfer uplift tension from a concrete wall to the footing? Or is this a calculation I need to check? Also, how is the shear (in the X direction of the drawing,from wind load) transferred from the wall to the footing? See the attachment. Thanks.

 

[BridgeSmith]

The development length definitely needs to be calculated. In your case, it's the development length for a hook in tension. It would be more correctly be called something like 'embedment depth', since what is calculated is the distance from the critical section (the interface of the wall and footing) to the outside of the hook at the bottom.

 

[slickdeals]

I would be concerned with getting adequate anchorage of the wall rebar into the slab at the roof for uplift, based on the proportions you have shown.

 

[Struct2468]

Slickdeals, this was just an example. The roof is just shown so you can tell that the wall is braced.

 

[KootK]

Sweet, this is one of my hot button issues.

1) This needs to be recognized as an anchorage issue and not a development issue. They are related, but difference.

2) Conspicuously, in my opinion, there is no code guidance that I know of to calculate the anchorage capacity of developed, cast in place bars.

3) In the absence of code guidance, I've investigated this by a) ACI 318 appendix D provisions and b) post installed dowel provisions. My conclusions are as follows:

3a) For generously spaced, small bars in "infinite" concrete masses, development generally will provide anchorage.

3b) Where demand is more concentrated, as with dense shear wall zones, development generally will not provide anchorage.

 

[DaveAtkins]

If you have uplift across the wall-footing interface, then yes, you need to check development length of the bar in the wall and the hook in the footing.

You show a pinned connection. Shear is transferred by shear-friction, so per Code the bars should be fully developed both in the footing and in the wall. But if the shear is low, I would not be too concerned.

DaveAtkins