Simplified Analysis Method for Tendon Force Degradation in Super-Long-Distance Tensioning of Prestressed Concrete Beams Considering Friction
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摘要: 在市政桥梁建设规模日趋壮大的今天,为了减少对毗邻建筑的影响,充分利用有限的空间,开始出现了越来越多的预应力大跨径桥梁。由于预应力钢丝束与混凝土桥梁之间的摩擦导致预拉力的损失对桥梁的力学性能存在显著的影响,且整个混凝土桥预应力钢丝束的布置错综复杂,钢丝束与混凝土的接触具有高度非线性特征,通常需要建立精细化模型以及接触单元来模拟混凝土梁与钢丝束的接触行为,导致计算不容易收敛且耗时较长。为了揭示预应力钢丝束张拉过程中摩擦对钢丝束拉力的影响,建立了考虑摩擦影响的预应力混凝土梁张拉施工简化模型。该简化模型通过非线性弹簧单元模拟钢丝束与混凝土梁之间的摩擦行为,仿真分析程序主要由等效摩擦单元以及迭代算法组成,计算中只需要设定节点坐标和摩擦系数,即可自动迭代得到准确的摩擦力大小。计算结果表明,所提出的简化模型计算精度高,有效避免了不收敛的问题。Abstract: 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.
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