预制节段逐跨拼装架设施工吊挂系统受力分析

Force Analysis of Suspending System for Span-by-Span Assembling and Erection of Precast Segments

为解决预应力混凝土梁桥预制节段逐跨拼装架设过程中预应力简支束张拉影响、临时吊杆拆除优化、首节段倾角预抬量等问题,以郑州桃花峪黄河大桥北侧堤内引桥为例,通过建立可快速计算、结果可靠的简化有限元模型,对以架桥机、临时吊杆和混凝土主梁组成的吊挂系统的受力进行分析,结果表明:预应力简支束张拉引起主梁反拱,使临时吊杆力分布急剧恶化,跨中吊杆力减小,梁端附近吊杆力增大;拆除临时吊杆进行体系转换的最优次序为从跨中至梁端对称进行,大部分吊杆可一次拆除,其余吊杆需放松后拆除;边挂边拼施工工艺首节段倾角预抬量为13.6mm/3.84m。

To provide solution to the problem of influence from tensioning of the prestressing strands for simply-supported girder and to the optimization of removal of the temporary suspenders and pre-raising amount of the inclination angle of the first segment in the process of span-by-span assembling and erection of precast segments of the prestressed concrete girder bridge,the north approach bridge of Taohuayu Huanghe River Bridge in Zhengzhou on the inner side of the river dyke was cited as an example.The forces of the suspending system formed by the overhead launching gantry,temporary suspenders and concrete main girder for assembling and erection of the precast segments of the bridge were analyzed,using the simplified finite element model that could fulfill rapid calculation and could produce reliable calculation results.The results of the analysis indicate that the tensioning of the prestressing strands for simply-supported girder can cause the main girder to camber inversely and make the force distribution of the temporary suspenders become dramatically worsen,the forces of the midspan suspenders reduced and the forces of the suspenders nearby the girder ends increased.The optimal sequence of removal of the temporary suspenders for system transformation is that the removal should proceed symmetrically from the midspan towards the ends of the girder.Most of the suspenders can be removed in one time while the rest of the suspenders need to relaxed first before removal.The pre-raising amount of the inclination angle of the first segment of the bridge to be constructed by the suspending and assembling technology is 13.6 mm/3.84 m.