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A pre-tensioned concrete member of section 200 mm × 250 mm contains tendons of area 500 mm2 at the centre of gravity of the section. The pre-stress in tendons is 1000 N/mm2. Assuming modular ratio as 10, the stress (N/mm2) in concrete is
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Correct Option: B
Pretension force, P = Ast Ps
= 1000 × 500
= 5000 kN
strain in concrete = strain in steel
| EcBc = | = 10.10 N/mm2 | 200 × 250 - 500 |
Stress in steel = strain in concrete × Es
| = | × Es | Ec |
= 10 × 10.10
= 101.01 N/mm2
Final stress = 1000 – 101.01 = 899N/mm2
| Pc = | = 9.08 N/mm2 | 200 × 250 - 500 |
