concrete deep beam question

[nongamer12]

does the horizontal face/skin reinforcing of a concrete deep beam need to be hooked into the column supports for development? thanks for any help/thoughts; let me know if you need more information.

 

[slickdeals]

I don't believe so, unless there is reversal of moments at the supports and you are using the skin reinforcing as flexural reinforcing (based on strain compatibility analysis)

 

[ishvaaag]

slickdeals makes the interesting exception of the skin steel being used as flexural reinforcing.

It may depends upon the code but the traditional methods of determining the required longitudinal and transversal steel for deep beams precisely acknowledge the fact of that steel is required there to reinforce against tensile stresses, i.e., more or less are precisely within the exception brought by slickdeals.

With a FEM program able to do plane stress on plates it is very easy to ascertain the pattern and magnitude of stresses in RC deep beams; everything tensile must be properly cared for, and be anchored beyond

 

[dcarr82775]

If the skin steel is just per the code then I see no need to provide hooks into the columns.

 

[BAretired]

Sorry, I guess I'm not clear on terminology. Skin steel is the nominal bars on each face above the bottom steel, right? Why would it not have to be developed into the column? Is it because it is not required in the strut and tie model?

BA

 

[dcarr82775]

BA, yes that is what I referred to as skin steel. IMO it does not need to be developed because its primary purpose is crack control, not strength and will typically be developed by the time it is needed away from the supports.

 

[hokie66]

I sense that some here are talking about a deep beam (non-flexural member), some about a flexural beam which is deep enough to require side face reinforcement. But then, the answer to the OP's question may be the same for both cases.

 

[ron9876]

If you have reinforcing steel it is there to resist some type of tension. The only reason that it wouldn't need to be hooked at the ends is that it is not in tension at that location and it is far enough away from the area that needs tension steel that it can be developed as a straight bar.

If you have a wide column or a wall you could extend it far enough but in general I think that the typical situation will require hooks. Deep beam skin reinforcement should be hooked.