2013年3月上第42卷第5期
D0I;10. 7672//sgjs2013050067
施工技术
CONSTRUCTIONTECHNOLOGY
某在建三跨连续梁桥跨中下挠原因及改造恢复分析
李杰，陈准，冯冠杰
（郑州大学土木工程学院，河南郑州450001）
【摘要】建立某支架施工的3跨连续梁桥有限元模型，分析施工中该桥跨中下揽变形过大的原因，依据变形后当前结构状态反推结构约束、受载状态，按照“顶升为主，压重为辅"的原则给出改造恢复方案，对悬臂压重、跨中分级顶升的改造恢复实施过程进行详细分析。通过分析可以得出，桥渠跨中下挠是由于跨中部分支架过早拆除引起，但桥架结构处于安全状态；变形后结构分析模型可以通过修正只受压支承的刚度、不受力支承退出工作的方式模拟部分支架拆除；采用悬臂端各压重1000kN，跨中分级顶升力3200kN可以恢复到桥梁部分拆架前的设计状态，恢复改造达到了预期效果。
【关键词】桥梁工程；连续架桥；满堂支架；挠度；改造
【中图分类号】TU746.3;U441;U448
【文献标识码】A
【文章编号】1002-8498(2013)05-0067-05
AnalyzingtheDownwardDeflectionofaMid-span
ContinuousGirderBridge andRetrofitting
Li Jie, Chen Huai, Feng Guanjie
( School of Civil Engineering, Zhengzhou Unitersity, Zhengzhou, He'nan 450001, Chine)
Abstract: Finite element model was built for a three-span continuous bridge to analyze the reason for the unusually large downward deflection at the mid-span of the bridge observed during its construction. The restraint condition and loading state of the bridge were derived according to its current deformation and retrofiting scheme was proposed following the principles of jacking as main method and weighting as assistant. The retrofitting construction process, which includes applying weight to the cantilever and phased jacking of the mid-span was analyzed in detail. The analysis result shows that the mid-span developed unusually large deflection due to the early removal of some mid-span supports, which did not endanger the safety of the bridge. Removal of the support can be simulated on the deformed structure by modifying the stiffness of compression-only supports and removing stress-free supports. By a three-stage jacking of the mid-span with 200kN each and applying a weight of 1 000kN at each cantilever end, the bridge was restored to its state before the removal of the supports. The retrofitting achieved the desired effect.
Key words : bridges; continuous girder bridges; full supports; deflection; retrofitting
1
工程概况
某高速公路跨河设计2幅3跨预应力混凝土连续箱梁桥，跨径布置为（45+70+45）m。单幅桥主梁采用单箱单室箱形截面，箱梁底板按照1.8次抛物线变化，根部梁高3.92m，跨中粱高1.92m，桥面横向宽12.75m；主梁为C50混凝土，主墩为C30混凝土。按照施工图设计文件，大桥采用落地支架现浇施工，完成下部结构施工后，首先浇筑主梁中跨
【作者黄介】李杰，副教授，博士，E-mail:publie_li@126.com
【收聘日期】2012-06-19 万方数据
67
70m及边跨距主墩19m的双悬臂梁，共计108m，在 19m悬臂端位置设置接缝和预应力连接器，完成第 1次混凝土浇筑养护后进行第1次预应力张拉，随后进行两侧边跨26m的混凝土浇筑及预应力张拉，然后张拉剩余预应力束，进行桥面二期施工，最后落架成桥。接照施工步骤，首先进行左辐桥跨中及 19m边跨悬臂部分的混凝土浇筑，体混凝土养护到施工图纸规定强度后，进行第1次预应力张拉；在进行剩余边跨混凝土浇筑前，考虑到预应力筋已经张拉，于是拆除了跨中部分支架，在拆除过程中中