波形钢腹板矮塔斜拉桥施工过程力学性能分析

Analysis of Load Bearing Performance of Corrugated Steel Web Extradosed Bridge During Construction Process

为指导波形钢腹板矮塔斜拉桥施工,对该类型桥梁的施工全过程进行力学性能分析。以(58+118+188+108)m的朝阳沟特大桥为研究对象,采用MIDAS/FEA有限元软件建立有限元模型,对其施工全过程进行计算。计算结果表明:施工过程中张拉悬臂顶板预应力束使主梁悬臂端轻微下挠,对悬臂施工主梁悬臂端竖向变形的影响远小于张拉斜拉索和浇筑梁段混凝土产生的影响;悬臂根部顶、底板应力在合龙束张拉时应力增量较大,应在施工中重点关注;斜拉索索力受施工阶段的影响不大,索力分2次张拉调整到成桥索力是合适的;矮塔斜拉桥桥塔和主梁刚度较大,两桥塔塔顶位移在悬臂施工过程中基本为0,顶推力作用下一侧桥塔塔顶向边跨桥台侧偏位约5cm,另一侧桥塔塔顶向边跨桥台侧偏位约4cm,可抵消后期运营中桥塔向跨中的偏位。

To provide reference for the design and construction control of the extradosed bridge with corrugated steel webs, the load bearing performance of the bridge of such type during the overall construction process was analyzed. The Chaoyanggou Bridge with span arrangement of （58＋118＋188＋108） m was cited as an example in this study. The MIDAS/FEA finite element software was used to establish the finite element model of the bridge to do calculation of the overall construction process. The results of the calculation demonstrate that the tensioning of the prestressing tendons in the top plates of the cantilevers during the construction process causes the ends of the main girder cantilevers slightly deflect, the influence of which on the vertical deformation in the ends of the main girder cantilevers is far smaller than the influence of stay cable tensioning and girder segment concreting. The increment of the stress in the top and bottom plates at the root of the cantilevers during the tensioning of prestressing tendons for closure is great, which should be given much concern during the construction. The cable forces of stay cables do not expose much to the influence of construction stages, and it is reasonable to adjust the cable forces to the level in the completed bridge state by two stages of tensioning. The stiffness of the pylons and main girder of the extradosed bridge is great, and the displacement at the pylon tops during the cantilever construction process is almost zero. Under the incremental launching force, the top of one pylon offset about 5 cm towards the side span abutment and the top of another pylon about 4 cm towards the side span abutment, possible to counteract the displacement of the pylons towards the midspan during the operation period. K