多塔悬索桥需通过主缆与中主鞍座问的摩擦力平衡由各跨之间荷载不同所导致的主缆不平衡张拉力,主缆与鞍座间的抗滑移安全问题是多塔悬索桥发展面临的核心问题之一;二者的摩擦系数则是多塔悬索桥设计的基础参数。以典型的大跨度多塔悬索桥——武汉鹦鹉洲长江大桥为研究对象,对于其主缆与鞍座问的摩擦与滑移特性进行模型试验,就主缆与鞍座问摩擦特性的试验模型设计、测试方法、测点布置以及主缆与鞍座问滑移时刻的判别依据等关键问题进行研究。研究表明:根据实桥主缆与鞍座间的实际接触及受力情况进行模型设计,并在此基础上通过测试数据的合理选取实现二者问滑移时刻的准确判别以及索股张拉力的准确测试是模型试验研究的关键问题;不同类型及不同位置的测试数据对于主缆和鞍座间滑移的敏感程度不同;模拟主缆与鞍座抗滑移特性试验名义摩擦系数实测值均值为0.473;通过在承缆槽内增加两片铸钢金属隔板的方式能够提高模拟主缆与鞍座问的摩擦力,此时名义摩擦系数实测值均值增至0.552。
In muhi-pylon suspension bridge, the unbalanced tension in main cable induced by unbalanced load of different spans is withstood by the friction force between main cable and saddle. The slippage resistance of main cable and saddle is one of the key problems of multi-pylon suspension bridges, and the frictional coefficient is the basic design parameter. The friction and slippage characteristics between main cable and saddle of the Yingwuzhou Yangtze River Bridge in Wuhan are investigated through model test. The key problems such as design method of model, the measurement method, the arrangement of test instruments and the discrimination of slippage occurrence moment between main cable and saddle are studied. The results show that the accurate simulation of the contact situation and mechanical characteristics of actual condition, the precise judgement of slipping moment and the accurate measurement of tension in cables are key procedures in model test. The sensitivities of measurement data with different types and locations to slippage between main cable and saddle differ from each other. The average value of frictional coefficients between main cable and saddle is 0. 473. By adding two cast steel plates in notch of saddle, the average measurement results of frictional coefficient increases to 0. 552.