刚性索悬索桥主缆张拉施工控制方法

Construction Control Method for Tensioning of Main Cables of Rigid Cable Suspension Bridge

为掌握刚性索悬索桥施工过程中桥梁真实的应力和线形状态,针对刚性索悬索桥的主缆在塔上张拉,其索力形成机理为主动受力的特点,研究计入主缆外包钢套筒、吊杆外包钢套筒作用的主缆张拉有限元法,并采用该方法对无应力索长控制法、张拉力控制法、塔顶有效索力控制法和跨中有效索力控制法4种主缆张拉控制应力方法确定的成桥状态进行比较。结果表明:无应力索长法与张拉力控制法的索力差距十分微小、主缆的存余有效索力与常规悬索桥模型的较为接近、成桥状态的变形最小,较利于结合构件安装线形的调整控制成桥线形。经有限元模拟和张拉控制应力修正,对某刚性索悬索桥进行了施工控制,结果表明实桥测试数据与理论计算符合良好。

To grasp the real stress and alignment condition of the rigid cable suspension bridge in the construction process, in view of the characteristics that the main cables of the bridge are tensioned on the tower and the formation mechanism of the cable forces shows the way of ac- tive load bearing, the finite element method for tensioning of the main cables taking account of the effect that the main cables and suspenders are encased in steel sheaths is studied and the com- pleted bridge state determined by the finite element method is compared with that determined by the 4 stress control methods for tensioning of the main cables, such as the unstressed cable length method, tensioning force method, tower top effective cable force method and midsparl effective cable force method. The results of the comparison indicate that the cable force differences between the unstressed cable length method and the tensioning force method are very slight. The remaining effective cable forces of the main cables are close to those of the regular suspension bridge models and the deformation of the completed bridge is the least, which is conducive to the tuning and control of alignment of the completed bridge based on the adjustment of alignment of the structural component installation. After the finite element simulation and modification of the control stress of tensioning, the construction control of an actual rigid cable suspension bridge has been carried out and the results prove that the measured data of the bridge are well coincident with the theoretical calculations.