倒退分析法确定拉索中钢绞线的张拉力

Tension Control for Strands in Cables Based on Reverse Analysis

提出使用倒退分析法得到每根钢绞线的初张力。通过分析各次钢绞线张拉后及张拉前的状态,推导出各阶段拉索应力的相互关系,可以由最后一个阶段的拉索应力逐步计算出每根钢绞线的初张力。通过使用该方法对金婺大桥单根换索过程的模拟表明:在拆索的过程中剩余钢绞线的拉力是增大的;在张拉的过程中,已有钢绞线的拉力是减小的。通过使用倒退分析法得到的钢绞线初张力进行换索,可得到均匀的、闭合的索力,即换索前后,结构的状态没有发生变化。利用倒退分析法,不仅可以计算新建桥梁拉索中每根钢绞线的初张力,还可以确定旧桥换索过程中每根钢绞线的张拉力。

The reverse analysis method was proposed to obtain the initial tension of each strand in cable.By analyzing the status of strands before and after each stretching,the relationship among the stress of strands in each stretching stage was derived,therefore,the initial tension of each strand can be calculated step by step from the stress of strands in the last stage.The simulation of single cable replacement at Jinwu bridge shows that the tension of formerly installed strands increases in strand relaxing and decreases in strand stretching.With the initial tension of each strand obtained from the reverse analysis method,evenly stress distribution on the cable section with closed form can be obtained,that is,the stress status of the whole struture keeps unchanged before and after the cable replacement.With the reverse analysis method,not only the initial tension of each strand in cables on newly built bridges can be obtained,the stretching tension of each strand in cable replacement of existing bridges can also be determined.