千吨级变宽悬浇挂篮设计

Design of Thousand-Ton-Class Form Traveler with Variable Width in Cantilever Casting

武汉大道跨铁路斜拉桥为138m+(81+41)m独塔双索面预应力混凝土箱梁斜拉桥,主梁为非对称单侧变宽截面双边箱结构,采用挂篮悬浇施工,最大悬浇节段重达800余吨。为解决桥下净空受限,变幅、超宽双边箱主梁悬浇施工难题,设计分体式多主桁与整体式变宽底模平台、低高度底模走行梁悬浇挂篮体系,承载力达1 000t。该挂篮体系由主桁系统、底模系统、模板系统、吊挂系统、平衡及锚固系统、走行系统、防护平台等组成,通过主桁与底模分步走行及3次体系转换方式实现主梁悬浇施工。采用MIDAS Civil平面模型和ANSYS空间实体模型进行仿真计算,得出挂篮和主梁应力和变形均满足要求。该桥采用该挂篮系统进行主梁悬浇施工,实现了特殊条件下的多组挂篮走行,变幅、超宽箱梁悬浇等作业。

The cable-stayed bridge crossing railways on the Wuhan Avenue is a single pylon prestressed concrete box girder cable-stayed bridge with double cable planes and with span arrangement of 138 m＋ （81＋41） m. The main girder, an asymmetrical double-edge-box structure with variable section only at one side, is constructed by cantilever casting using form travelers, and the longest segment cast weights up to more than 800 t. Due to the limitation of the clearance under the existing railway bridge and the complexities of the cantilever casting construction of double- edge-box main girder, the form traveler system used for the cantilever casting having a bearing capacity of 1 000 t and equipped with separated multiple trusses, monolithic bottom mould platform with variable width and low height bottom mould travelling beam was designed. Specifically, the form traveler system was composed of the main truss system, bottom mould system, formwork system, hanging system, balance and anchoring system, traveling system and the protection platform. The cantilever casting construction was realized via the step-by-step travelling of the main trusses and the bottom formwork and by way of three times of system transformation. The MI- DAS Civil planar model and the ANSYS three-dimensional solid model were adopted to carry out simulation calculation. The results of the calculation indicated that the stress and deformation of the form traveler and main girder were able to meet the relevant requirements. The application of the form traveler system to the cantilever casting construction of the main girder of the bridge assured the traveling of multiple sets of form travelers under special conditions and the cantilever casting of the very wide box girder with variable section.