The loss of prestress due to elastic shortening of concrete is least in

A uniformly distributed load intensity, $$w$$ acting on a simply supported prestressed concrete beam of span $$L,$$ producing a bending moment $$M,$$ at mid-span is to be balanced by a parabolic tendon with zero eccentricity at ends and eccentricity $$e,$$ at mid-span. The prestressing force required depends on

The kern area (core) of a solid circular section column of diameter, $$D$$ is a concentric circle of diameter, $$'d'$$ is equal to

The maximum bending stress induced in a steel wire of modulus of elasticity $$200$$ $$kN/m{m^2}$$ and diameter $$1$$ $$mm$$ when wound on a drum of diameter $$1$$ $$m$$ is approximately equal to