悬索桥短吊索索力测试的探讨

Study on tension testing of short hangers in suspension bridges

因难以准确确定吊索的计算长度和抗弯刚度,按照公式法计算短吊索的索力误差一般较大。以新沟河大桥悬索桥吊索索力测试为研究背景,分析了吊索的边界条件、抗弯刚度、计算索长及线密度等因素对索力测试精度的影响,表明公式法的简化假设对短吊索不适用。介绍了有限元法分析吊索索力的方法,按吊索的实际尺寸建立有限元模型,首先识别出吊索的抗弯刚度,然后建立各吊索的索力—频率对应表格,查表即可得到实测频率对应的索力。该方法应用到新沟河大桥的施工监控,证明是一种行之有效的方法。

Because it is difficult to accurately determine the effective length and bending rigidity of a hanger,the tension calculation of short hangers according to formula method may lead to big error.Taking the testing of hanger tension of the Xingou River Bridge as the research background,the effects of such parameters as boundary conditions,bending stiffness,effective length and linear density on the accuracy of the tension measurements are analyzed in detail.The results show that the simplifying assumptions of formula method are not suitable for short hangers.Hanger tension calculation with finite element method is introduced.The finite element model is established according to real condition.Firstly,the bending stiffness of hangers is identified;then corresponding relationship table of hanger tension-frequency should be established.The corresponding tension of a measured frequency can be obtained through looking up the table.The method has been applied to construction monitoring of Xingou River Bridge and proved to be an effective method.