跨繁忙航道超宽钢箱梁梁上运梁及分块安装方案研究

巴拿马四桥为巴拿马国内第一座公轨合建混合梁斜拉桥,桥面宽51m,中跨钢箱梁标准节段长13m,为典型超宽超重结构。桥位处通航要求高,施工期间不得占用航道,既有道路拥挤。针对这些问题,提出了一种创新的施工方案:边跨混凝土梁段采用挂篮对称悬浇施工,待混凝土梁和结合段施工完成后再架设钢箱梁;钢箱梁采用纵向分段、横向分块,通过索塔侧向提梁上桥面;梁上运梁至悬臂端桥面吊机处,尾部提梁前移并空中旋转90°,调整好姿态后再横向移梁进行匹配对位,对称张拉相应位置斜拉索。为了验证该施工方案的可行性,采用Midas civil建立了全桥有限元模型,对整个施工阶段进行了模拟计算,结果表明该方法存在横向偏载效应,但整个施工阶段结构安全可靠,可为今后同类桥梁架设提供参考。

Scheme Study of Transporting and Installing the Super Wide Steel Box Girder on Busy Navigation Channel

The Fourth Bridge across the Panama Canal will be the first hybrid girder cable-stayed bridge in Panama,with a deck width of 51 m and a standard section length of 13 m of medium span steel box girder.It is a typical super wide and super heavy structure.The navigation requirements at the bridge site are high,and the channel shall not be occupied during the construction period.The traffic on the existing roads are crowded.In view of these problems,in this paper an innovative construction scheme is put forward:the side span concrete beam section is constructed by symmetrical hanging basket,and the steel box girder is erected after the completion of the construction of the concrete beam and the joint section.The steel box girder is divided into longitudinal sections and transverse sections,and is transported to the bridge deck crane at the cantilever end through the side lifting beam of the pylon,and the rear lifting beam is moved forward and rotated 90° in the air,and adjusted after the posture is good,the beam is moved laterally for matching and alignment,and the cable at the corresponding position is tensioned symmetrically.In order to verify the feasibility of the construction scheme,Midas civil is used to establish the finite element model of the whole bridge and simulate the whole construction stage.The results show that the method has the effect of lateral eccentric load,but the structure of the whole construction stage is safe and reliable,which can provide reference for the similar bridge girder erection in the future.