290m空腹式刚构桥三角区施工技术

Construction Techniques for Triangle Area of a 290-m Span Open-Web Continuous Rigid-Frame Bridge

北盘江特大桥主桥为(82.5+220+290+220+82.5)m预应力混凝土空腹式连续刚构。为解决三角区上、下弦施工相互干扰,无法同步进行的问题,对该部位施工技术进行研究。采用上弦滞后于下弦2个梁段(先施工下弦、后施工上弦)的总体施工方案,并合理设计挂篮及支架系统。下弦采用挂篮并辅以扣索张拉施工,上弦采用支撑于下弦顶面的支架分段现浇施工,待上、下弦箱梁施工至11号节段后,利用上弦处挂篮浇筑三角区汇合段混凝土。

The main bridge of Beipan River Bridge is a prestressed concrete open-web continuous rigid-frame bridge with span arrangement（82.5＋220＋290＋220＋82.5） m.To tackle the problem that the construction of the upper and lower chords in the triangle area of the bridge would interfere with each other and the construction of the upper and lower chords could not be carried out in the same step,the construction techniques for the area were studied.It was determined through the study that the overall construction scheme of constructing the upper chord two segments of the lower chord late（i.e.the lower chord would be constructed first and the upper chord would be late） would be adopted and the form travelers and scaffolding system would be rationally designed.The lower chord was consequently concreted by the form travelers by the aid of tensioned fastening stays,the upper chord was concreted in situ in segments on the scaffolding supported on the top of the lower chord and after the construction of the box girders of both the upper chord and lower chord reached segment No.11,the form traveler on the upper chord was then used to concrete the joint sections of the triangle area.