RC Deep Beam Deflection Calculations

[asixth]

Hi Guys

I am using a wall as a deep beam and engaging the slabs as flanges. Is the theory the same for longterm deflection calculations for a deep beam as it is for a shallow flexural member (span/depth=2 ; span/thickness=40). I can find plenty of information regarding the flexural and shear strength but can't find much information dealing with deflections.

Regards

 

[ishvaaag]

Quite likely that is because deep beams are usually proficient in delivering deflection control. You may get conservative estimates of the deflection by thinking of the deep beam as a strut and tie truss device.

 

[DST148]

Try if thread507-9049 would help.
A quick search over the internet for deflection of deep concrete beams: The summary from the paper by Prabhat Kumar "Short term deflection of deep beams" published by ACI Journal August 1978 - Deflection of deep beam is considerably larger than that predicted by use of simple beam deflection formula with fully cracked section moment of inertia. The paper gives expressions for predicting deflections.........

 

[shin25]

Do you have very stringent deflection limitation which is much smaller than code may permit? If not, I don't see a reason for determining deep beam deflection.

 

[asixth]

the problem arises because it is a transfer member, so any longterm deflection which hasn't been preset will be reflected thru the stories.

 

[structSU10]

I would imagine that for a deep beam shear deformations may become more critical than flexural deformations. Also, I would think that due to the non-linear stress distribution that general deflection equations would not predict deflection very accurately.

I dont know if any FEA plate elements or such would give you an accurate stress distribution, but applying a long term factor to such a model may provide reasonable deflection results.

I think it comes down to figuring out and upper and lower bound to the solution in order to get a good understanding of what may occur.