外倾式钢拱桥施工控制关键技术

Key Technologies for Construction Control of Externally Inclined Steel Arch Bridges

某新建外倾拱桥采用主桥跨径69.514m的下承式组合梁钢系杆拱桥,采用先梁后拱分阶段逐步安装的施工方法。为确保成桥内力及线形满足设计要求,使用Midas/Civil有限元软件建立桥梁计算模型,基于倒拆和正装计算法开展施工控制。针对施工过程结构变形大、拱肋空间定位精度要求高、拱端张拉空间小及张拉设备数量限制、施工过程边界条件复杂等特点,结合施工关键工序研究,采用钢梁预拱度匹配制造、拱肋整体吊装、吊杆分批张拉、成桥后二次调索等关键控制技术,实现了拱肋快速精准定位,确保了结构受力安全和线形控制。施工控制结果表明:实测线形与设计线形吻合,索力偏差小于5%,满足设计要求,成桥状态良好。

A newly built externally inclined arch bridge adopts a through type composite beam steel tied arch bridge with a main bridge span of 69.514 meters.The construction method of gradually installing the beam and arch in stages is adopted.To ensure that the internal force and alignment of the completed bridge meet the design requirements,a bridge calculation model is established using Midas/Civil finite element software,and the construction control is carried out based on the reverse dismanting and formal installation calculation methods.As to the characteristics of large structural deformation during the construction process,high requirements for spatial positioning accuracy of arch ribs,small tension space at the arch end,limited number of tensioning equipment,and complex boundary conditions during the construction process,combined with research on key construction processes,key control technologies such as steel beam pre arch matching manufacturing,integral lfting of arch ribs,batch tensioning of suspension rods,and secondary cable adjustment after bridge completion are adopted to achieve rapid and accurate positioning of arch ribs.The safety of structural stress and linear control are ensured.The construction control results indicate that the measured alignment matches the designed alignment,with a cable force deviation of less than 5%and meeting the design requirements,and the bridge is in good condition.