Regarding deep beam design 2

[Nayan67]

Hi all,
I am trying to design a capping beam that meets the definition of a deep beam, with an a/d ratio of around 1.0. I am curious about the standard practice for designing such a beam in terms of shear and flexure. Is it mandatory to design the beam using the strut and tie model? Alternatively, can we use equations available for ordinary beams to calculate the stirrups for shear force, and rely on beam theory for the computation of the flexural reinforcement?

Regards,
Nayan

 

[HTURKAK]

If ( a) is span and a/d ratio of around 1.0, the beam is definitely deep beam. In this case , linear–elastic flexural theory and plane sections remaining plane after bending is no more valid and shear deformation dominates the behaviour.

You may design with STM modelling or follow the rules specified at your code .




Use it up, wear it out;
Make it do, or do without.

NEW ENGLAND MAXIM

 

[dik]

Strut and tie seems to be the easiest approach.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[ENGIRL]

for deep beams I used to use strut and tie method. I once used a second method that I found in the canadian concrete Handbook (Park & Paulay method) where you can use the regular equations (Mr, Vr,...) but with reducing d (leval arm) parameter (distance between rebar in tension and compressed fiber of concrete).I compared the results to the strut and tie method and the final design was similar. You can see the article from the book in the images below .

 

[dik]

b = width of the wall?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Nayan67]

Thank you so much everyone for your feedback.

 

[HTURKAK]

Yes .. b= width of the wall. I have an old German book with similar figures.I found the following doc. at SEFI and found useful .





Use it up, wear it out;
Make it do, or do without.

NEW ENGLAND MAXIM

 

[dik]

thanks...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[JohnRwals]

I guess this is a kind of grey area and STM itself is too liberal...
this topic is not clearly understood as a term 'disturbance' means.
For example, the above reference used distributed load; no difference for concentrated load condition?
Any data for pretension case like in the precast concrete walls? Just adjust compression strut and fy?
_JRW