Question

A pre-tensioned concrete member if section 200250 mm contains tendons of area 500 mm2 at centre of gravity of the section. The pre-stress in the tendons is 1000n/mm2.Assuming modular ratio as 10.The stress in(n/mm2) concrete is

Answer 1

#BAL

Using modular ratio area of tendons can be converted to equivalent concrete area. (Es/Ec=10) i.e (Ac/As =10)i.e Ac = 500 * 10 = 5000 mm2, Total area of concrete = 5000+ (200*250) mm2 = 55000 mm2.

Total Stress in concrete = P/55000 = (Area of Tendons * Prestress)/55000 = (500*1000)/55000 = 9.09.