大跨度斜拉桥施工过程中的索力控制方法

Method of Cable Tension Controlling in the Long-span Cable-stayed Bridge Construction

针对平行钢绞线斜拉索施工过程中的索力控制问题,根据逐根张拉的斜拉索施工工艺,建立了张拉过程中索-梁-塔的力学模型;并以斜拉索索力均匀为目标,按正装分析法推导了挂索时单根钢绞线的张拉力计算公式。在此基础上结合等值张拉法,消除了挂索期间温度变化对钢绞线张拉力的影响,并给出了施工和运营过程中的索力测量方法。北方某斜拉桥的工程实践表明:根据该方法确定的单根钢绞线张拉力进行张拉,能够得到较均匀的索力;不论单根钢绞线拉力还是总索力,误差都在5%以内,均能满足施工控制的精度要求;该方法可供同类型斜拉索施工参考。

In allusion to the cable tension controlling problem in the parallel strand stayed-cable construction, on the basis of construction techniques of applying tension loads one by one, the mechanical model of the cable-girder-tower in the process of construction was established. With the equal cable tension as a goal, the formula was deduced with the method of forward-analysis, which could be used to calculate the initial tension of each strand in construction. The effect of temperature variations on the initial tension could be eliminated by using the formula with the method of equivalent tension. Moreover, a method was proposed to measure the cable tension in the processes of construction and performing the function. Finally, the practice in one cable stayed bridge in the north indicated that 1 ） the uniform cable tension could be obtained by the proposed method; 2） the tension error range of whether a single strand or the whole stayed-cable was within 5%, and the result could meet the needs in construction control; 3） the method could provide reference for the similar stayed cable construction.