MSUK90 said:
but I still would like to know why "flexural reinforcement" affect is not considered in ACI and CSA even though its that much significant as per BS and Indian codes.
As said in several other previous posts, flexural reinforcement is included in both the ACI and CSA codes. The link posted by steveh49 is worth a look.
The following quotes are relevant to the discussion.
From ACI318-2008 Commentary:
"R11.2.2.1 — Equation (11-5) is the basic expression for
shear strength of members without shear reinforcement.11.3
The three variables in Eq. (11-5), λ (as a measure of
concrete tensile strength), ρw, and Vud/Mu, are known to
affect shear strength, although
some research data
indicate that Eq. (11-5) overestimates the influence of fc′ and
underestimates the influence of ρw and Vud/Mu. Further
information has indicated that shear strength decreases
as the overall depth of the member increases."
From the April 2020 issue of Concrete International (V42 No.4):
"The 2019 edition of the ACI 318 Code contains new
equations for calculation of concrete shear strength for
reinforced concrete members. The rationale for the
new equations is provided in Reference 2.
In brief, the
changes reflect observations that concrete member shear
strength is affected by the member depth and the percentage
of flexural reinforcement.
(My bold emphasis)
Doug Jenkins
Interactive Design Services