ANALYSIS OF EXTERNALLY PRESTRESSED TENDONS CONSIDERING INFLUENCE OF RELATIVE SLIP

Externally prestressed tendons have been used widely in repairing or retrofitting aged structures and new steel-concrete composite structures. Analytical methods for such structures, however, were not yet developed deeply enough because of the relative slip between the tendons and the deviators. In particular, the strain compatibility condition of tendons and the host structure, which is the fundamental hypothesis in conventional analysis methods, was no more available. The incremental stress induced by the deformation of the structure is of great importance in the analysis of such structures. Most existing methods in the literature are limited and only suitable for some certain types of structures or without considering the relative slip between tendons with deviators. This work investigated the kinematic relationship between the elongation of external tendons and the deformation of the host structures with the slip between the tendons and the deviators considered. A manipulation of linearizing this kinematic relationship yielded a general formula for the incremental stress of externally prestressed tendons caused by the deformation of the host structures. The stiffness matrix was also obtained explicitly. A new element was then developed for externally prestressed tendons considering the influence of the relative slip. Meanwhile, a simplified method for the evaluation of the incremental stress of externally prestressed tendons was proposed. Finally, some numerical examples demonstrated the convenience and accuracy of the proposed new element and simplified method.