Tendon model for nonlinear analysis of prestressed concrete structures

A tendon model based on the finite-element method, that can represent the interaction between tendon and concrete of the prestressed concrete member, is proposed. Especially for multitendon cases, this model is capable of simulating the slip of tendon in concrete duct so it can deal with the prestressing transfer of posttensioned structures and calculate unbonded prestressed structures more efficiently. Another relevant model is also proposed to represent friction and bond at the interface of tendon and concrete. By using these models, a numerical procedure is established for material and geometric nonlinear analysis of prestressed concrete structures, including time-dependent effects due to load history, relaxation of prestress, and creep and shrinkage of concrete. The procedure can predict the responses of pretensioned and bonded or unbonded posttensioned plane concrete structures such as elastic and plastic deformation, cracking, and damage patterns throughout their prestressing transfer and service-load history. A numerical example is presented to demonstrate the validity and efficiency of the present method. Comparison of computed results with experimental ones shows good agreement.