Abstract:
Shear reinforcement in Reinforced concrete beams depends upon various parameters such as
longitudinal steel ratio, aggregate type, strength of concrete, size of beam and types of loading.
These factors are not fully incorporated in ACI code provision for design of minimum shear
reinforcement. Zarari studied these factors on shear behavior of R.C beams analytically but
experimentally have not been validated. To validate these factor, experimental work was
undertaken on the shear behavior of ordinary strength reinforced concrete slender beams with
moderate longitudinal reinforcement. Based on the experimental work, Modification to Zarari’s
equation is proposed on shear behavior of R.C beams.
The experimental program consisted of testing of eight simply supported R.C slender beams
subjected to two concentrated loads with span to depth (a/d) ratio of 2.5.Test specimen were
divided into four groups based on amount and spacing of minimum shear reinforcement in RC
beams. Two specimens were prepared without shear reinforcement, two specimens were based
on ACI code provisions, two specimens were prepared according to Zarari’s (2003) equations,
and two with modified equations presented in this study. Ultimate shear strengths obtained in
this experimental program are compared to the analytical shear strengths calculated according
to ACI code, Zarari equation and the Modified Zarari equation. Test results shows that, the
proposed equation and Zarari equation gives better prediction of shear capacity of RC beams
than ACI. Based on the test data, it was also found that minimum shear reinforcement should
be such that it allows development of nominal flexural capacity in RC beams; accordingly a
new expression for calculating minimum shear reinforcement is also proposed which
incorporates all contributing factors.
