Dear colleagues,
I would like to know your opinions.
The strain distribution in the deep beam is no considered linear, and the shear deformations become significant when compared to pure flexure. At present, there are different definitions of deep beam. For example, deep beams are defined in the ACI-318 (2014) as flexural members having a clear span to depth ratio of less than 4.0. However, the deep beams are defined in the Eurocode 2, as members having a clear span to depth ratio of less than 3. There are also other codes with different definitions. There is no single consensus.
Why are there different criteria?
I will appreciate your opinions.
Thank you very much in advance.
Best regards,
The assumption of plane section remain plane cannot be used in the deep beam design. The strain distribution is not longer linear.
In Canadian CSA Code, STM is recommended as a method for shear design of deep beam. Unlike the ACI Code, the 1984 CSA Code uses the concept of shear span-to-effective depth ratio a/d rather than the effective span-to-depth ratio
ln/d for deep beam design.
STM of the ACI 318-02 is recommended as a most desirable method because it has lowest standard deviation although its predicted shear strength is relatively higher than that of ACI 318-99.
Ref: Soo-Yeon SEO, Seung-Joe YOON, Woo-Jin LEE. STRUCTURAL BEHAVIOR OF R/C DEEP BEAM WITH HEADED LONGITUDINAL REINFORCEMENTS,
13th World Conference on Earthquake Engineering,Vancouver, B.C., Canada
August 1-6, 2004,Paper No. 58.
portion of paper is attached
Dear Chitaranjan Pany,
Thank you for your comments. I will take them into consideration.
We have done some work on this topic, reaching conclusions about the prediction of the resistant capacity using the ACI code. For example:
Rodríguez, G.; Bonilla, J.; Hernández, J., Pudipedi, L. (2017): Study of the behavior of reinforced concrete deep beams. Estimate of the ultimate shear capacity, Journal of Construction, Vol. 16, No 1, Chile, ISSN: 0717-7925, E-ISSN: 0718-915X. p. 43-56. doi: 10.7764/RDLC.16.1.43.
In the above paper, conclusions are reached on the resistance prediction of the deep beams using Strut and Tie (STM) method according to ACI code. It is observed that the ACI code offers very conservative resistant capacity values for deep beams.
Thank you very much for your kind attention and cooperation.
Best regard,
In a shallow beam there is shear deformations, but it's magnitude is small and can be neglected. So, I think, ACI and Eurocode 2 have different definition for the word "small".
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