GATE 2023 RCC & Prestressed Concrete Quiz 50

The loss of prestress due to wobbling effect is because

A post tension beam section drawn below consists of three cables of 100 mm² area. Initial prestressing in cable is 600 N/mm². If tensioning is done successively one by one, the loss of prestress in second cable will be {m = 6}.

For a pre-tensioned beam, young’s modulus of steel and concrete are 200 GPa and 35 GPa, respectively. If the beam is post-tensioned and age of concrete at transfer is 8 days and ultimate creep coefficient is 1.6, what is the level of sustained stress in concrete at the level of steel. If the loss due to creep is three times the loss due to shrinkage.

A prestressed concrete beam 300mm wide and 400mm deep is prestressed by concentrically placed tendon. The span of the beam is 10m bas a super imposed load of 5kN/m. Then the prestressing force necessary, So that the tension is just avoided at the soffit of mid section would be � kN.

(Round of to 1 decimal places)

A concentrically pretensioned prestressed concrete beam of dimension 200 mm × 300 mm has area of steel equals 600 mm². The stress in steel initially is 1200 MPa and modular ratio is 8. The prestressing force (in kN, correct upto 1 decimal place) immediately after transfer will be -