Stress Distribution Between Steel & Concrete:
As per the basic assumption, plain RCC section before bending remains plain after bending. It is clear that in the flexural member at a specific point the compressive stress and the tensile stress are proportional to their distance from N.A ( Neutral axis). As the bond between concrete and steel becomes excellent, strains induced in concrete as well as in the steel will be equal.
Let strain in concrete and strain in steel be designated by ec and et
According to Hooke’s law
Stress/Strain = Moduli of elasticity
Therefore
Where t = Permissible tensile stress in steel.
Es = Moduli of steel.
and
c’ = Stress in concrete in level with tensile steel.
Ec = Modulus of concrete.
But
Or 
From the above expression, it is evident that the stress in the steel is m times the stress in concrete surrounding it.
