a. A symmetrical rectangle box section prestressed concrete beamof external width of 300 mm and external depth of 600 mm with auniform thickness of 40 mm is prestressed with 7 numbers straightsteel wires of 7 mm diameter located at a distance of 15 mm fromthe bottom of the soffit and 5 number of 5mm diameter of the steelwires located at the 575 mm from the bottom of the beam . The wireswere initially tensioned on the prestressing bed with an initialprestress of 1500 N/mm2 . The beam is subjected to point load of 48+ 0.2 (54) kN at the center of the beam and a uniformly distributedload of 20 kN/m entire length of the beam with a length of 10 m.Calculate the resultant stresses at the end and mid span sectionwith neat stress distribution diagram. Assume the density of theconcrete is 24 kN/m3 . Use BS8110 code
b. In the above problem, how to control the resultant stressessuch that they do not exceed 25 N/mm2 at mid span section.
