3×340m公铁合建多塔斜拉桥结构体系研究

Research on Structural System of 3×340 m Multi-tower Cable-stayed Rail/Road Bridge

珠机城际金海特大桥主桥采用(58.5+116+3×340+116+58.5) m四塔三主跨斜拉桥,为国内首座公铁平层合建的多塔斜拉桥。金海桥塔多联长,采用何种结构体系提高结构刚度、减小温度效应及改善结构受力是结构设计的关键。为此,在总结既有多塔斜拉桥经验的基础上,比选了半漂浮体系、刚构-半漂浮体系、梁式支承体系以及首次在多塔斜拉桥应用的刚构-连续体系。通过对4种结构体系的刚度,结构受力等分析,并考虑构造要求和经济性,推荐采用刚构-连续体系,即两中间塔墩梁固结,两边塔梁固结、塔墩分离。该体系有效提高了结构整体刚度,主梁、桥塔及斜拉索受力较优,同时降低了温度效应的不利影响,车桥动力仿真分析结果表明,桥梁的振动性能良好,行车舒适性优。

Jinhai super major bridge of the intercity rail line connecting Zhuhai downtown and airport becomes the first multi-tower cable-stayed rail-road bridge in China. Its main bridge is a four-tower cable-stayed bridge with spans of(58.5+116+3×340+116+58.5) m. Because of the multi-tower and long connected girder, the key in structural design of JinHai grand bridge is what structural system should be adopted to improve structural stiffness, reduce temperature effect and improve bearing ability of the structure. Therefore, on the basis of the experiences of existing multi-tower cable-stayed bridges, the semi-floating system, rigid-frame-semi-floating system, girder support system and rigid-frame-continuous system first used in multi-tower cable-stayed bridges are compared. Based on the analysis of the stiffness and structural stress of the four structural systems and the consideration of the structural requirements and economy, rigid-frame-continuous system is recommended, that is the two middle towers are consolidated to piers and beams, and two side towers are separated from piers with beams consolidated. For this kind of system, the overall stiffness of the structure is effectively improved, and the main girder, tower and cable-stayed cables are better stressed, while the adverse effects of temperature are reduced. The results of vehicle-bridge dynamic simulation analysis show that the vibration performance of the bridge is good and the riding comfort is excellent.