温州瓯江北口大桥主桥设计关键技术

Key Techniques of Design of Main Bridge of Oujiang River North Estuary Bridge in Wenzhou

温州瓯江北口大桥主桥为主跨2×800m的三塔双层桥面钢桁梁悬索桥,上层通行6车道高速公路,下层通行6车道一级公路。针对该桥多塔、大跨、双层桥面的特点,对其支承体系、加劲梁、中塔及其基础设计关键技术进行研究。基于结构受力合理性以及运营安全等因素,该桥支承体系采用纵向在加劲梁梁端设置阻尼器;竖向在桥塔及边墩处设置竖向支座,并对桥塔处进行压重;横向在加劲梁与塔柱间设置抗风支座。综合考虑运输及安装、抗风稳定性、使用功能及经济性等因素,加劲梁采用正交异性钢桥面板与主桁结合的整体式钢桁梁,全桥4跨连续。为节省造价、降低后期维养工作量,中塔采用纵向A形钢筋混凝土结构,在中塔主缆鞍槽中设置多道竖向隔板,以提高主缆钢丝与鞍槽间的摩擦力,保证主缆抗滑移安全。为提高结构刚度、降低造价,中塔基础采用防撞能力强的大型沉井基础。

The main bridge of the Oujiang River North Estuary Bridge in Wenzhou is a doubledeck steel truss girder suspension bridge with three towers and with the main spans of 2×800m.The upper deck of the bridge is designed to carry 6-lane expressways while the lower deck to carry6-lane Class I highways.In the light of the characteristics that the bridge has the multiple towers,long spans and double decks,the key techniques of the design of the support systems,stiffening girder,intermediate tower and the foundation for the tower of the bridge have been studied.In comprehensive consideration of the factors like the structural force rationality and the operation safety,the support systems are designed in such a way that in the longitudinal direction of the bridge,the dampers are arranged at the ends of the stiffening girder,in the vertical direction,the vertical bearings are arranged at the towers and side piers and the parts of the stiffening girder at the towers are counterweighted and in the transverse direction,the wind bearings are arranged between the towers and the stiffening girder.Also in comprehensive consideration of the other more factors like the transportation,installation,wind stability,service function and construction cost,the stiffening girder is designed into an integral steel truss girder that the orthotropic steel deck plates and the main truss are composited and the four spans of the whole main bridge are made continuous.To save the construction cost and minimize the future maintenance work load,the intermediate tower is designed as an A-shape reinforced concrete structure in the longitudinal direction and in the intermediate tower saddle trough,the multiple rows of the vertical partition plates are arranged so that the frictional forces among the main cable steel wires and the saddle trough can be improved and the anti-slip safety of the main cables will be guaranteed.To improve the structural stiffness and reduce the cost,the large open caisson foundation that has strong collision resistance capacity is designed for the intermediate tower.