As per Indian standard code of practice for prestressed concrete $$(IS:1343-1980)$$ the minimum grades of concrete to be used for post-tensioned and pre-tensioned structural elements are respectively

A concrete beam of rectangular cross section of $$200\,\,mm \times 400\,\,mm$$ is pre-stressed with a force $$400$$ $$kN$$ at eccentricity $$100$$ $$mm.$$ the maximum compressive stress in the concrete is

The partial factor of safety for concrete as per IS: 456-2000 is

The flexural strength of M30 concrete as per IS: 456-2000 is