What are secondary losses in integral and continuous prestressed structures

Question

Accepted Answer

Secondary losses in integral and continuous prestressed structures refer to the loss of prestress due to factors other than elastic shortening.

Secondary losses can be caused by creep, shrinkage, relaxation, and anchorage slip.
Creep is the gradual deformation of concrete under sustained load.
Shrinkage is the reduction in volume of concrete as it dries.
Relaxation is the loss of prestress over time due to the relaxation of steel.
Anchorage slip is the movement of the prestressing steel within the anchorage.
Secondary losses can result in a reduction in the prestress force and an increase in deflection and cracking.
To account for secondary losses, engineers typically increase the initial prestress force or use a time-dependent analysis.
Integral and continuous prestressed structures are particularly susceptible to secondary losses due to their long spans and lack of joints.

Top Mott MacDonald Bridge Engineer interview questions & answers