万州长江三桥桥塔设计

Design of Pylons of Third Wanzhou Changjiang River Bridge

万州长江三桥为双塔混合梁斜拉桥,跨径布置为(4×57.5+730+4×57.5)m。桥塔采用具有欧式建筑风格的钻石塔型,既减小了水下基础规模,又与当地建筑相得益彰。桥塔由上、中、下塔柱和下横梁构成,南塔高248.12m,北塔高208.2m,两塔下横梁以上保持一致。由于地形的限制,南、北塔下塔柱高度相差悬殊,为充分考虑两塔刚度差的影响,直接在全桥总体模型中进行桥塔分析。采取3项措施(对下横梁进行分节段浇筑、优化下塔柱与下横梁截面及对下塔柱增设竖向预应力)有效解决了北塔下塔柱与下横梁形成的横向框架刚度过大的难题。采用横向框架杆系模型与节段细部实体模型结合的方法,确定了理想的索塔锚固区预应力布置形式。受力分析表明,桥塔各构件均满足规范要求。

The Third Wanzhou Changjiang River Bridge is a double‐pylon hybrid girder cable‐stayed bridge with span arrangement （4 × 57 .5＋730＋4 × 57 .5） m .The pylons of the bridge are the diamond‐shape pylons featuring the European architecture style .The pylons of such kind not only reduce the scales of their underwater foundations ,but also are in good harmony with the ar‐chitectural environment nearby the bridge site .T he pylons are made up of the upper ,middle and lower columns and lower cross beams .The south pylon is 248 .12 m high ,the north pylon is 208 .2 m high and above the lower cross beams ,the design of the two pylons is kept identical .Restricted by the topography at the bridge site ,the height difference between the lower columns of the south and north pylons is great and the design of the pylons is hence difficult .To thoroughly consider the rigidity difference influences of the two pylons in the design ,the pylons were analyzed directly in the global model of the whole bridge .Three measures （e .g .concreting the lower cross beams in segments ,optimizing cross sections of the lower columns and lower cross beams and adding verti‐cal prestressing to the lower columns） were taken and the problem that the rigidity of the trans‐verse frame formed by the lower columns and lower cross beam of the north pylon was too great was effectively resolved .Besides ,the ideal prestressing layout in the anchorage zones in the pylons was determined ,using the method combining the link model of the transverse frames and the solid model of the segment details .The analysis of the force conditions of the pylons proved that the va‐rious components of the pylons could satisfy the relevant requirements in the codes .