部分斜拉桥拉索与索鞍摩擦系数试验研究

Experiment of the Friction Coefficient Between Cable and Saddle of Partially Cable-stayed Bridge

拉索与索鞍间的摩擦力对部分斜拉桥索鞍部位拉索锚固抗滑移起着至关重要的作用。通过制作索塔节段足尺模型,开展拉索钢绞线和索鞍分丝管之间的摩擦系数测试试验。试验结果表明:1)钢绞线外防护形式、初始平衡态张拉力、索鞍半径大小对摩擦系数具有显著影响;2)随着初始平衡态张拉力增大,钢绞线与分丝管间的摩擦系数呈明显下降趋势,索鞍处设置短PE护套情况下的钢绞线摩擦系数降幅最大,全索长PE护套包覆情况次之,裸钢绞线变化幅度最小;3)初始平衡态张拉力与索鞍半径大小均影响钢绞线对分丝管壁压力的大小,进而影响摩擦系数值,而分丝管壁所承受的压力越大,摩擦系数越小。工程应用中应考虑摩擦系数变化的影响。

The frictional force between the cable and the saddle plays a crucial role in the resistance to slip of the cable at the saddle of a partially cable-stayed bridge.A full-scale model segment of tower was constructed to conduct friction coefficient testing between the cable′s steel strand and split tube of the multi-tube bundled saddle.The test results show that:1)The external protection form of the steel strand,initial balanced tension,and saddle radius have a significant influence on the friction coefficient.2)As the initial balanced tension force increases,the friction coefficient between the steel strand and the split tube shows a noticeable decrease trend,the greatest reduction in friction coefficient is observed when the wire rope is covered with a short PE sheath at the saddle,followed by the case that the entire length of the cable is protected by a PE sheath,while the bare strand shows the smallest change in friction coefficient.3)Both the initial balanced tension and saddle radius affect the pressure exerted by the strand on the inner wall of the split tube,thereby influencing the friction coefficient,the greater the pressure on the tube inner wall,the smaller the friction coefficient.The effects of variations in the friction coefficient should be considered in engineering applications.