超长服役期钢斜拉桥换索关键技术研究

Research on the Key Technology of Cable Replacement for Ultra-Long Service Period Steel Cable-Stayed Bridge

服役中的大跨度斜拉桥换索施工其关键技术包括两方面,一是借助现代计算分析和监测方法确保施工过程结构安全,二是通过方案优化确定最优施工工期。本文以一座服役33年、检测后评定为4类旧桥的大跨径钢斜拉桥为工程背景,对换索施工关键技术进行研究。该桥主梁损伤严重,工期紧迫,斜拉索更换对主梁受力安全和工期影响较大,因此制定两塔同步对称换索、两塔同步交叉换索、先南塔后北塔换索和先北塔后南塔换索四种方案。采用有限元仿真分析方法对四种换索方案施工过程进行受力分析,并综合施工周期以确定最优换索方案。采取自动化监测技术,对换索过程索力和主梁应力进行监测,按理论值预测进行控制,以确保大跨度钢斜拉桥换索施工过程结构安全。

The key technologies of cable replacement construction on old long-span cable-stayed bridges in service include two aspects,one is that the structural safety should be ensured during construction with the help of modem calculation,analysis and monitoring methods,the other is determination of optimal construction period through scheme optimization.In this paper,a long-span steel cable-stayed bridge is as engineering background that has been in sendee for 33 years and has been evaluated as class 4 old bridge after inspection,and the key technology of cable replacement construction is researched.The replacement of stay cables has a great impact on the stress safety of the main beam because the damage of main beam is serious,and the construction period is tight.Therefore,four kinds of replacement schemes have been formulated,the four schemes are synchronous and symmetrical cable replacement construction of two towers,synchronous cross cable replacement construction between two towers,cable replacement construction of the south tower before the north tower and cable replacement construction of north tower before south tower.Through the finite element simulation analysis of four replacement sequences of stay cables,the reasonable cable replacement sequence is determined combining with the construction period.The automatic monitoring technology is adopted to monitor the cable force and the main beam stress,and compare with the theoretical analysis value to ensure the structural safety during the cable replacement construction process of long-span steel cable-stayed bridges.