Study on prestress loss and safety performance of retard-bonded prestressed cast-in-place piles.

The retard-bonded prestressed cast-in-place pile (RBPCP) represents a novel anti-floating structural technology with prominent advantages, including low cost and improved crack resistance. The structure and design methodology of the RBPCP and a new arrangement form for the retard-bonded prestressed reinforcing bar (RBPR) were presented. The test equipment and two-stage loading method were developed to facilitate static uplifting load tests of RBPCPs. Test study and numerical analysis on the prestress loss were conducted. The results indicate that the prestress loss in the pile increases with pile depth. Comparative analysis between required prestress and reserve prestress indicates that such loss exerts a negligible influence on the lower pile part. Moreover, the entire pile can maintain a compressive stress state as long as the tension load reaches the designed uplift bearing capacity. Therefore, the RBPCP demonstrates outstanding safety performance and is suitable for widespread application in engineering.