天津永和斜拉桥换索后的索力调整

结合天津永和斜拉桥的换索与调索实践,在分析换索后全桥结构性能变化的基础上,阐述索力调整的目标、原则,利用平面杆系有限元程序和影响矩阵法基本原理,采用试算法确定出索力调整方案,分析索力调整的效果。调索过程中的监测结果表明,索力调整后,全桥索力接近目标值,索力分布趋于均匀,桥面线形、塔位均得到明显的改善,调索并未引起主梁混凝土产生过大的拉应力,试算法是一种实用性较强的可行方法。调索方案的优选应考虑尽量避免使运营多年的老桥结构受力状态发生突变,以保证调索过程中结构的安全。天津永和斜拉桥的调索实践为今后PC斜拉桥的调索工程提供了较为重要的参考。

Cable Force Adjustment after Cable Replacement for Tianjin Yonghe Cable-stayed Bridge

Cable force adjustment is an effective measurement to reduce cable force errors after replacement of cables in existing PC cable-stayed bridges.Combined with Tianjin Yonghe Bridge,the objective and principles for adjustment of cable forces were provided on basis of analyzing changes of structural behaviors in this bridge.Based on the planar beam finite element method and the influence matrix method,a trial-and-error calculation method was applied to determine the optimal cable force adjustment scheme.Thereafter,some structural behavior changes after adjustment were analyzed.Monitoring results show that(1) all cable forces approach designed value and their distribution became reasonable after adjustment,the deflection of deck and position of the top of tower were improved;(2) during adjustment,little tensile stress changed in concrete beam.The trial-and-error calculation method is a reasonably practical method.A perfect adjustment scheme must avoid changing structural or mechanical state of old bridge over many years in order to ensure safety during cable force adjustment.The practice of Yonghe Bridge possessed an event of significance for cable adjustment of many old prestressed concrete cable-stayed bridges.