Title: Modeling of Sliding Behavior of Unbonded Tendons in Post-Tensioned Concrete Members

Author(s): Yu Huang and Thomas H.-K. Kang

Publication: Structural Journal

Volume: 115

Issue: 4

Appears on pages(s): 1153-1164

Keywords: contact formulation; friction; nonlinear finite element; posttensioned concrete; sliding

DOI: 10.14359/51702066

Date: 7/1/2018

Abstract:
This paper discusses a nonlinear finite element formulation comprising contact and engineering elements in modeling post-tensioned concrete members. The study focuses on modeling of the sliding behavior observed in post-tensioned tendons. Detailed discussion is presented for the modified node-to-segment contact formulation, by which the bonding interface is discretized and physically modeled. Perfectly unbonded, partially bonded, and fully bonded conditions are considered by introducing frictionless and frictional contact. Post-tensioned tendons are modeled by the nonlinear truss element and are embedded into the nonlinear reinforced concrete beam element. The embedding element comprises elastic Euler beam element with very large stiffness. The nonlinear anchorage element and the prestressing procedure are also proposed to simplify and to properly model the complex jacking process. The proposed formulations were implemented in a nonlinear finite element code developed in MATLAB. Validation of the proposed formulations and implementations were carried out in several numerical studies. The proposed formulation performed with a reasonably good accuracy in reproducing global flexural behavior as well as predicting localized prestress loss and redistribution.