In shear design of an $$RC$$ beam, other than the allowable shear strength of concrete $$\left( {{\tau _c}} \right),$$there is also an additional check suggested in $$IS$$ $$456$$-$$2000$$ with respect to the maximum permissible shear stress $$\left( {{\tau _{c\,\,\max }}} \right).$$ The check for $${{\tau _{c\,\,\max }}}$$ is required to take care of

Assuming concrete below the neutral axis to be cracked, the shear stress across the depth of a singly-reinforced rectangular beam section