15. What are the three major types of reinforcement used in prestressing?
Spalling reinforcement: They are created behind the loaded area of anchor blocks and this initiates breaking away of surface concrete. These stresses are induced by strain incompatibility with Poisson’s effects or by the shape of stress trajectories.
Equilibrium reinforcement: This is needed in situations where there are several anchorages in which prestressing loads are applied sequentially.
Bursting Reinforcement: Tensile stresses are initiated in the course of prestressing operation and the largest bursting stress happen where the stress trajectories are concave towards the line of action of the load. The bursting reinforcement is needed to resist these lateral tensile forces.