The purpose of reinforcement in pre-stressed concrete is A. To provide adequate bond stress B. To resist tensile stresses C. To impart initial compressive stress in concrete D. All of the above

The correct answer is D. All of the above.

Reinforcement in pre-stressed concrete is used to provide adequate bond stress, resist tensile stresses, and impart initial compressive stress in concrete.

• Adequate bond stress is required to ensure that the reinforcement and concrete act together as a unit.
• Tensile stresses are caused by bending, shear, and other loads. Reinforcement is used to resist these stresses and prevent the concrete from cracking.
• Initial compressive stress is imparted to the concrete by pre-stressing. This compressive stress helps to offset the tensile stresses that are caused by loads, and it also makes the concrete more resistant to cracking.

Without reinforcement, pre-stressed concrete would be very weak and would not be able to withstand the loads that it is designed to carry.