考虑拉扭耦合效应的空间主缆扭转计算方法

Torsional calculation method of spatial cable with consideration of tension-torsion coupling effect

由于钢丝集束体组成主缆的扭转刚度是受多因素影响的变量,目前空间主缆的扭转还没有可靠的计算方法。分析了影响空间主缆扭转刚度的主要因素,建立了主缆集束体考虑拉扭耦合效应的解析计算模型,推导了拉扭耦合引起的抗扭力矩的计算公式。在此基础上,讨论了主缆半径、主缆张力及扭转角对主缆扭转刚度的影响规律。从施工控制的角度分析了扭转刚度、索夹刚臂、吊索张拉次序及索夹预偏角对主缆扭转角的影响。研究结果表明:由于拉扭耦合效应的影响,在体系转换过程中随着主缆张力和扭转角的增大主缆扭转刚度呈明显的非线性增长;在施工控制中,为减小主缆的扭转变形,可在索夹安装时设置与成桥时索夹扭转方向相同的预偏角,利用吊索力通过索夹刚臂给主缆施加反向扭矩来实现对主缆扭转的主动控制,以抵消或减小主缆的扭转变形。

Because torsional stiffness of main cable which contains a plurality of steel wire is affected by many factors,there is no reliable calculation method for spatial cable torsion at present.The chief factors influencing torsional stiffness were analysed in this paper.The analytical calculation model with consideration of tension-torsion coupling effect was established,and the formula of resistance torsion moment of main cable caused by tension torsion coupling was deduced.On this basis,the influence law of main cable radius,tension and torsion angle on torsional stiffness was discussed.The impact of torsional stiffness,cable clamp rigid arm,suspender tensioning sequence and cable clamp preformed angle on main cable torsion angle was analyzed from the perspective of construction control.The results show that the torsional stiffness of main cable presents nonlinear growth trend during the system transition with the increase of tension and torsion angel because of the influence of tension-torsion coupling effect.In the construction control,in order to reduce torsion deformation of main cable,the bias angle of cable clamps can be set towards the rotation direction of cable clamp at the stage of finishedbridge at the time of assembly.The active control of the main cable torsion can be realized through a reverse torque to the main cable,that is generated by applying the hanger force to the rigid arm of cable clamp.This method can offset or reduce torsional deformation of the main cable.11 figs,10refs.