However, the stress relaxation of prestressing tendons, the occurrence of cracks and shrinkage of concrete, and the deformation of anchorages result in loss of prestress. This will decrease the service life of the structures.
The deformation of concrete, the relaxation of the prestressed steel strand, the corrosion of the steel strand, and the creep of concrete will cause the loss of prestress. However, the prestress loss has not been solved well, so it is important to detect the prestressed concrete structure effectively.
In their findings, the strength and stiffness loss of prestressed tendons are slower than those of traditional prestressed steel strands.
The long-term loss of prestress
is governed by long-term behavior factors such as creep and shrinkage of concrete.
Loss of prestress prediction on nondestructive damage location algorithms, SPIE, Smart Structures and Materials, 2446-60-67.
Prediction of PRC beam's loss of prestress based on vibration test, Journal of Vibration and Shock, 22(3): 95-97 http://dx.doi.org/10.3969/j.issn.1002-0268.2015.10.009.
Loss of prestress
in the stays is also shown in Figure 6.
The intention was to check any vulnerability, namely, the differences in the slab stiffness caused by a loss of prestress
. During the first flexural test, the level of the prestress load at each rod was 180 kN, whereas the level of the prestress in the second flexural test was 110 kN.
Due to the friction or bond of concrete, the stress along the tendon usually changes, and load cell at the beam ends can only obtain the total loss of prestress .
Based on the probabilistic analysis model adapted in this study, the probability analyses were conducted, which indicate that the long-term loss of prestress does not reject the normal distribution at each time, and its discreteness gradually become larger with the extension of time.
Loss of prestress due to creep was examined for one specimen by monitoring GFRP strains over a 12-day period following fabrication.
The average loss of prestress following release of the clamps due to camber was 16.1 percent.