Simplified Analysis Method for Tendon Force Degradation in Super-Long-Distance Tensioning of Prestressed Concrete Beams Considering Friction

With the increasing scale of municipal bridge construction today， and in order to minimize the impact on adjacent buildings while making full use of limited space， prestressed long-span bridges are becoming more and more common. The friction between the prestressed steel tendons and the concrete bridge leads to prestress loss， which significantly affects the mechanical properties of the bridge. Due to the complex arrangement of the prestressed steel tendons within the concrete bridge and the highly nonlinear characteristics of the contact between the tendons and the concrete， it is usually necessary to establish a refined model with contact units to simulate the contact behavior between the concrete beam and the steel tendons. This often leads to challenges in achieving computational convergence and results in prolonged simulation time. In order to investigate the influence of friction on the tensile force of prestressed steel tendons during the tensioning process， this paper proposes a simplified model for the tensioning construction of prestressed concrete beams that accounts for friction effects. The simplified model simulates the friction behavior between the steel tendons and the concrete beam by a nonlinear spring element. The simulation analysis program is mainly composed of equivalent friction elements and iterative algorithm. By simply defining the nodal coordinates and friction coefficient， the accurate friction force can be automatically determined through iteration. The calculation results demonstrate that the proposed simplified model achieves high accuracy and effectively avoids non-convergence issues.