Abstract:
Over the last century, the design for shear in reinforced concrete beams has
been uncertain. The reason for this uncertainty is the lack of clear
understanding of the true nature of load carrying mechanism. Researchers
around the world have developed several shear design procedure as a
remedy to this uncertainty. Most of them are empirical and some are rational
which use various mathematical representations of load carrying mechanism.
Almost all of these mathematical models are complicated and accuracy of is
rather low compared to empirical methods.
With the advancement of concrete technology and introduction of new
methods, the improvement of accuracy of shear design methods is rather
unmatchable when compared with flexural design. However, some of the
new shear design methods were adopted by codes of practice and the design
formulae were modified by introducing various empirical factors based on
test. So the shear design has now become very much empirical.
Some of the developed rational methods give good representation of the load
carrying mechanism of beams. The method proposed here with the objective
of developing a rational yet simple method, also assumes the load carrying
mechanism of a beam as a truss. The tension carrying member represents the
stirrups and the concrete portion is represented by compression member.
For this proposed=method, the compression carrying concrete member is
idealized as a cylindrical element applied with axial compression. The
behavior ~of this idealized cylinder is modeled by using mathematical
technique'S like Isotropic and Anisotropic analysis. This developed method is
..•compared with several key codes of practice using available test data for
accuracy. It is found that the proposed method is giving sound representation of the test
results compared with most other codes of practice. According to the
comparison, it is clear that this method is only second to Japanese code of
practice.
