空间主缆扭转特性与扭转效应试验研究

Test study on spatial cable torsion properties and torsion effect

空间主缆自锚式悬索桥由空缆状态转换为成桥状态的过程中,两鞍座间主缆将产生一定的扭转。以杭州江东大桥为研究背景,在综合考虑经济性、模型材料、制作工艺以及实验室条件等的基础上,确定了试验模型的几何缩尺比为1∶15。设计了吊索张拉锚固系统、缆索位形测量装置;提出了主缆截面方位线的概念,并基于新型缆索位形测试装置的测量值,建立了主缆截面扭转角计算方法。进行了吊索索夹不同预偏角、不同吊杆张拉力的模型试验,研究了主缆截面的扭转特性与扭转效应的规律。试验研究表明:吊索索夹横向预偏角度对该索夹处主缆截面扭转角起决定性影响,对相邻吊索索夹主缆截面扭转角的影响几乎可以忽略,相邻吊索索夹之间的扭转角几乎成线形变化;吊索力较小时,主缆扭转角接近终值,主缆抗扭刚度较低;索鞍附近主缆扭转规律较复杂,有待进一步研究。

When converting self-anchored suspension bridge with spatial cable from initial construction state to finished dead state,the main cable between the two saddles would be under certain torsion. In the background of Jiangdong Bridge,a experimental model proportion of 1 ∶ 15 was determined in the consideration of economy,model material,fabrication technology,and laboratory condition etc. Based on the model,a sling tensioning and anchoring system and a metrical equipment for cable configuration were designed. The experiment put forward a concept of main cable section bearing line,and a set calculation method for main cable section torsion angle depending on the measurements from the new metrical equipment. A series of model tests were conducted for different bias angles of the sling clamp,different tensioning forces of sling. And studied the regularity of the torsional properties and the its torsion effect. The results indicate that the transverse bias angle of the clamp is the decisive influence factor to the torsion angle in its own main cable section,but almost no effect to other place. The changing of the adjacent clamps is nearly linear. When the tensioning force is small,the torsion angle is closed to terminal value and the torsional stiffness of the main cable is small. For the complication of the main cable torsion regularity near the saddles,further studies need to be conducted.