A prestressed concrete rectangular beam of size $$300\,\,mm \times 900\,\,mm$$ is prestressed with an intial prestressing force of $$700$$ $$kN$$ at an eccentricity of $$350$$ $$mm$$ at midspan. Stress at top due to prestress alone, in $$N/m{m^2}$$ is

A prestressed concrete beam has a cross-section with the following properties: Area $$A = 46,000\,\,m{m^2},$$ $${\rm I} = 75.8 \times {10^7}\,\,m{m^4},$$ $${Y_{bottom}} = 244\,\,mm,$$ $${Y_{top}} = 156\,\,mm.$$ It is subjected to a prestressing force at an eccentricity $$'e'$$ so as to have a zero stress at the top fibre. The value of $$'e'$$ given by

A rectangular simply supported prestressed concrete beam of span $$L$$ is subjected to a prestressing force of $$P$$ acting centrally at end sections and the prestress tendons are parabolically draped with maximum eccentricity of $${e_{\max }}$$ at the mid span section. The uniformly distributed upward load $$(W)$$ on the beam due to prestressing will be: