不对称转体斜拉桥球铰应力分析及不平衡力矩计算

Stress analysis and unbalanced moment calculation of ball joint in asymmetric rotating cable-stayed bridge

【目的】探究不平衡力矩工况下多点支撑转体系统的受力状态和不平衡力矩的计算方法,以保证转体结构受力安全,也为转体前的平衡配重提供依据。【方法】采用有限元软件ABAQUS建立了不对称斜拉桥的局部有限元分析模型,对比分析了五级不平衡力矩工况下的球铰和转台应力。通过量化应力集中对不平衡力矩预估精度的影响,改进了传统不平衡力矩的计算公式。【结果】球铰边缘应力远高于内部;不平衡力矩的增加会引起球铰两侧的接触应力发生反向变化;多点支撑可降低球铰和转台应力峰值;改进公式的预估值与模拟输入值吻合较好。【结论】仿真模拟结果表明了转体结构在不平衡力矩工况下设计的安全性;同时,改进的不平衡力矩预估模型计算方便,能降低传统称重施工成本,缩短工作时间,且精度较高,可为实桥转体提供技术支撑。

[Purposes]The paper aims to explore the stress state and calculation method of unbalanced moment of multi-point support swivel system under unbalanced moment condition,so as to ensure stress safety of the swivel structure and provide basis for balancing counterweight before swivel.[Methods]The local finite element analysis model of asymmetric cable-stayed bridge was established by the finite element software of ABAQUS,the stress of the ball joint and turntable under the condition of five-stage unbalanced moment was compared and analyzed.By quantifying the influence of stress concentration on the prediction accuracy of unbalanced moment,the traditional calculation formula of unbalanced moment was improved.[Findings]The stress at the edge of the ball joint is much higher than that at the inside.The increase of unbalanced moment will cause reverse change of contact stress on both sides of the ball joint.Multi-point support can reduce the peak stress of the ball joint and turntable.The predicted value of the improved formula is in good agreement with the simulating input value.[Conclusions]The simulation results show the safety of the swivel structure under unbalanced moment condition.At the same time,the improved unbalanced moment prediction model is convenient to calculate,can reduce the traditional weighing construction cost,shorten the working time,and has high accuracy,which can provide technical support for the swivel of real bridge.