Spalling reinforcement for pre-stressing in anchor blocks

Question

Why is spalling reinforcement essential for pre-stressing works in anchor blocks?

Answer 1

Reinforcement of anchor blocks in pre-stressing works comprises:

a) Bursting reinforcement
b) Equilibrium reinforcement
c) Spalling reinforcement
Bursting reinforcement is required wherever tensile stresses are induced.
For equilibrium reinforcement, it is required whenever there are a number of anchorages in which pre-stressing loads are applied one after another.
During pre-stressing, spalling stresses are produced in the region at the back of the anchor blocks loaded faces. At the area between two anchorages, there is an amount of concrete enclosed by compressive stress trajectories. Forces are created in the opposite direction to the applied forces so in turn the generated force pushes the concrete out of the anchor block.