混凝土自锚式悬索桥吊索张拉优化研究

Study of Hanger Cable Tensioning Optimization for Self-Anchored Concrete Suspension Bridge

广西钦州子材大桥为跨径布置(65+158+65)m的双塔三跨混凝土自锚式悬索桥,采用先梁后缆法施工。为保证施工过程中的安全性和经济性,采用"相邻索同步张拉的依次张拉法",提出主跨吊索从塔柱向跨中张拉和从跨中向塔柱张拉2种方案。建立非线性有限元模型,对体系转换过程中吊索、主梁、桥塔的内力和变形进行分析,并根据张拉批次、接长杆数量和长度、千斤顶数量及鞍座顶推次数等进行经济性比选分析,确定适合该桥的体系转换施工方案。研究结果表明:主跨吊索选择从跨中向塔柱依次张拉的方案,在不增加施工千斤顶数量的前提下,避免了全桥吊索分级多次张拉带来的不便,提高了体系转换施工效率。体系转换完成后桥梁的线形和内力均满足要求,张拉方案的实际应用效果良好。

The Zicai Bridge in Qinzhou city ,Guangxi Province ,is a （65 ＋ 158 ＋ 65） m three-span self-anchored concrete suspension bridge with two towers .During the construction process , the stiffening girder was erected ahead of the installation of the main cables .To ensure the safety and economy of the bridge construction ,the sequential tensioning method ,by which the adjacent hanger cables were tensioned in parallel ,was adopted .The two schemes of tensioning the main span hanger cables respectively from the two towers towards the midspan and from the midspan to -wards the towers were proposed .The non-linear finite element model of the bridge was established to analyze the internal forces and deformation of the hanger cables ,main girder and towers during the system transformation process .Moreover ,the contrastive analysis of the economy of the two schemes was carried out taking into account of the tensioning batch ,the amount and the length of the lengthening pieces ,the number of the jacks used and the times of incremental launching done＆amp;nbsp;for the saddles ,and based on the analysis results ,the construction scheme which was favorable for the system transformation of the bridge was determined .The results of the study demonstrated that when the main span hanger cables were tensioned by a sequence from the midspan towards the towers ,the inconvenience caused by the phased-in and multiple times of hanger cable tensioning of the whole bridge was avoided on the premise that no extra jacks would be added during the con-struction process ,and the efficiency of system transformation construction was improved .After the system transformation ,the geometry and internal force of the bridge met the requirements , and the effect of the practical application of the tensioning scheme was sound .