鄂东长江公路大桥结构设计方案研究

Study of Structural Design Schemes for Edong Changjiang River Highway Bridge

为研究千米级混合梁斜拉桥结构设计,以鄂东长江公路大桥为依托,通过结构计算与试验模拟,从钢-混凝土结合段位置的选择、索距、桥塔、主梁、主梁钢-混凝土结合段等方面对该桥结构设计方案进行研究。结果表明:钢-混凝土结合段设置在中跨侧距桥塔中心12.5 m处,结合段位置主梁的变形和内力均较小;中跨标准梁段宜采用15 m索距,边跨宜采用7.5 m索距;该桥桥面以上塔高为180.5 m;索塔锚固形式采用钢锚箱方案,并设置弧形预应力筋减少和控制主桥索塔锚固区外壁裂缝;主梁采用PK断面,可充分发挥全截面的性能;采用优化的"混凝土后设承压板"的钢-混凝土结合段型式,应力和刚度过渡较为平顺。

To study the structural design of hybrid girder cable-stayed bridges having span length longer than 1 000 m,the Edong Changjiang River Highway Bridge was cited as an example and through structural calculation and testing simulation,the structural design schemes for the highway bridge were studied from several aspects of selection of the steel and concrete joint section locations,cable spacing,pylons,main girder and steel and concrete joint sections of the girder.The results of the study indicate that if a steel and concrete joint section is located on the side of the central span at a distance of 12.5 m to the center of a pylon,the deformation and internal force in the main girder at the joint section will be little.The stay cable spacing on the typical segments of the central span should be preferably 15 m while on the segments of side spans should be 7.5 m.The height of pylons of the bridge above the deck is 180.5 m.The steel anchor boxes are used for the anchorage in the pylons and the arc prestressing tendons are arranged to reduce and control cracking in the external walls of the anchorage zones.The main girder is designed as the PK（Pasco-Kennewick Bridge） cross section that can bring the performance of total cross section into full play.The optimized steel and concrete joint sections of ＂setting compression plates behind concrete＂ are adopted and the transition of stress and rigidity there is smooth.