大跨度悬索桥索股抗弯刚度对锚跨张力测试精度的影响研究

Analysis of cable bending stiffness effect on test accuracy of anchor span tension for long-span suspension bridge

为研究索股抗弯刚度对张力测试精度的影响,基于能量法推导了计入索股抗弯刚度和忽略索股抗弯刚度影响的悬索桥锚跨索股在两端铰接时索股张力和自振频率的关系,考虑到悬索桥索股边界条件的复杂性,结合动平衡法得出了索股在一端铰接一端弹性支承时索股张力与自振频率之间的相关表达式。通过算例,对所得表达式的精度及有效性进行了验证,结果发现索股的抗弯刚度对索股张力控制精度的影响较大。工程应用研究则表明,索股抗弯刚度对测试精度的影响,主要由索股张力产生的应力刚度与索股抗弯刚度之间的比值决定;锚跨索股边界条件的不确定性,对控制精度也产生较大影响,施工锚跨张力控制过程中,结合提出的最小二乘法,能有效地解决该问题,并能大幅提高索股张力控制精度。

In order to study the strands of main cables bending stiffness effect on the test accuracy of an- chor span tension for long-span suspension bridge, relative expression between the natural frequency and the anchor span tension of the anchor span tension with considering the bending stiffness or not were de- duced based on the energy method when the two ends are hinged,considering the boundary conditions of the anchor span tension is complex, the expression was also deduced based on the dynamic balance meth- od when one end of the anchor span tension is hinged,another is elastic support. The accuracy and effec- tiveness had been verified with some classic examples, the conclusions indicate that the strands of main cables bending stiffness have a great effect on the test accuracy of anchor span tension. The study of the application of engineering shows that the strands of main cables bending stiffness influence on the test precision is mainly decided by the ratio of stress stiffness produced by tension to bending stiffness. The uncertainty of the anchor span boundary conditions also has considerable impacts on the precision of con- trol, during the process of construction tension control. It can effectively solve the problem and can great- ly improve the anchor span tension control precision with the proposed least square method.