摘要
天津永和大桥为5孔一联、主孔跨径260 m、双塔双索面、塔墩固结、连续呈漂浮体系的PC斜拉桥。与中跨合龙段置换相匹配,利用拆除合龙段后形成两半桥的时机,通过调索来改善主梁线形是国内既有PC斜拉桥维修的一个先例。通过对比分析合龙段拆除后状态与原桥竣工状态在桥面线形、索力等结构性能上的差异,并依据中跨合龙段拆除前已然存在的中跨局部下挠量,确立了主梁线形调整的目标和调索幅度,利用平面杆系有限元计算分析拟定并优选了调索方案,提出了主梁线形调整的施工控制原则。施工监测结果表明,所有调索步骤完成后,主梁线形调整最终达到了预期目标,调整后的索力更趋于均匀,调整过程兼顾了主梁混凝土应力、塔位以及劲性骨架轴力的变化,保证了结构的安全。
Tianjin Yonghe Bridge is a prestressed concrete cable-stayed bridge which has one continuous and floatable structural system with 5 spans, double pylons, double cable planes and fixed with the piers. The length of its main span is 260 meters. Accompanied with replacement of the closure segment in the midspan, after removing the closure segment and thus forming two half bridges, the alignment of main girder was improved by means of adjusting cable forces, which is a precedent in maintenance of existing prestressed concrete cable- strayed bridges. The structural differences in the deck alignment and cable force between after removal of the closure segment and original completion were comparatively analyzed. According to the deflection value at the midspan of the middle span before removing the closure segment, the alignment adjustment target value, adjustment range and increment of cables were established. An adjustment scheme of cable forces was studied and optimized. Then some construction control guidelines were provided. Construction monitoring results showed, after adjustment of cable forces, the target value of alignment of the main girder was achieved, and cable forces of the whole bridge became well-proportioned. During adjusting, concrete stress of the main girder, position of the top of tower, and axial force of the stiffening frames were considered synchronously. This practice may provide some valuable experience for other cable-stayed bridge in need of adjusting the alignment of main girder in the finished state.
出处
《公路交通科技》
CAS
CSCD
北大核心
2009年第6期98-103,共6页
Journal of Highway and Transportation Research and Development
基金
交通部西部交通建设科技资助项目(200731822340)
关键词
桥梁工程
线形调整
调索
PC斜拉桥
拆除合龙段
bridge engineering
alignment adjustment
cable force adjustment
prestressed concrete cable- strayed bridge
removing the closure segment
