After pre-stressing process is completed, a loss of stress is due to A. Shrinkage of concrete B. Elastic shortening of concrete C. Creep of concrete D. All the above

The correct answer is: D. All of the above

After pre-stressing process is completed, a loss of stress is due to shrinkage of concrete, elastic shortening of concrete, and creep of concrete.

• Shrinkage of concrete is a decrease in the volume of concrete due to the loss of water. It is a time-dependent process that occurs after concrete has been placed and finished. Shrinkage can cause cracking in concrete if it is not properly controlled.
• Elastic shortening of concrete is a decrease in the length of concrete due to the application of stress. It is a reversible process that occurs when the stress is removed. Elastic shortening is usually small compared to the other losses of stress that occur after pre-stressing.
• Creep of concrete is a time-dependent increase in the strain of concrete under constant stress. It is a permanent deformation that occurs when concrete is subjected to sustained loads. Creep can cause a loss of prestress in prestressed concrete members.

The magnitude of the losses of stress due to shrinkage, elastic shortening, and creep depends on a number of factors, including the type of concrete, the curing conditions, the age of the concrete, and the magnitude of the applied stress.