shear strength prediction of non flexural rc deep beams using various approaches.

TLDR: In this paper, a strut-and-tie approach is presented for determining shear behavior of deep beams, strut and tie method is rational and unified approach which represents complex behavior of beams into simple truss model which is applicable where Bernoulli- Euler beam theory is not valid, generally termed as disturbed region (D-regions) in which nonlinear strain variation is observed.

Abstract: In this study, shear behavior of RC non flexural deep beams which are predominant in shear were studied. According to ACI 318-08 (1) , deep beams are classified as shear span to depth (a/d) ratio less than 2.5, shear capacity of deep beam was worked out by ACI 318 equation 11.30 and 11.31 and results were compared with modified ACI equation by Tan et al ( 2) . Strut and tie approach is also used which are suggested by many codes like ACI 318 (appendix A) and Euro code 2 (3) . Shear capacity found from STM analysis was compared with ACI 318 equation and modified ACI equation. Parameters considered for the study are a/d ratio ranging from 0.5 to 1 and compressive strength of concrete (25MPa, 50Mpa), shear reinforcement varied between 0 to 0.17%. It is seen from the analysis that both ACI 318-99 and modified ACI equation does not consider the effect of shear span to depth (a/d) ratio and STM approach was found much rational. Reinforced concrete deep beams are commonly used in high rise buildings, offshore structures and complex foundation systems. Deep beams are more predominant in shear rather than flexure. This shear action in the beam leads to complex stresses, compression in a diagonal direction and tension in a perpendicular direction. An arch action is usually seen as the force transferring mechanism of deep beams, failure is seen as web compression failure or shear tension failure Shear strength of deep beams depends on various parameters like compressive strength of concrete, shear reinforcement, shear span to depth ratio. ACI 318-99 Code suggests design criterion for the shear strength of deep beams is known to be conservative with a large safety margin. In ACI Eq. (11-29), it is assumed that diagonal cracking occurs at the same shear strength as for slender beams, but that the shear strength of the concrete is greater than the shear force causing diagonal cracking. This paper also presents a strut and tie approach of determining shear behavior of deep beams, strut and tie method is rational and unified approach which represents complex behavior of beams into simple truss model which is applicable where Bernoulli- Euler beam theory is not valid, generally termed as disturbed region (D-regions) in which non-linear strain variation is observed . STM is very popular in designing of Corbels, complex foundations, beam-column joint. Provisions for the design of deep beams using a strut-and-tie model have been included in several codes and guidelines for practice,