主跨292 m非对称上承式拱桥结构设计研究

Research on Structural Design of Asymmetric Arch Bridge with Main Span of 292 m

上承式拱桥是山区桥梁首选桥型之一,通常采用对称结构形式。大跨度非对称上承式高速铁路拱桥工程实例少,结构设计的一些关键技术参数尚待研究。张吉怀铁路酉水大桥采用主跨292 m上承式非对称钢管混凝土拱桥跨越酉水河。该桥主拱横向由两片拱肋组成,每片拱肋采用2根内径1500 mm钢管及联接系组成的桁架形式,拱上立柱采用桁架式钢立柱,上部结构采用刚构连续梁+钢混组合梁体系,拱肋结构及钢立柱采用耐候钢。拱肋采用扣挂法悬拼,刚构混凝土梁采用挂篮悬臂浇筑,钢混组合梁钢梁采用整节段吊装,桥面板采用预制安装施工。为研究该桥结构受力特点,验证桥梁结构的合理性与安全性,通过有限元对结构的刚度、强度、稳定性等各项指标进行了分析。研究表明,采用不对称拱桥更好地适应了桥址处地形条件,减小了桥梁跨度,经济性更优。结构各项指标均满足规范要求,结构安全可靠。

Deck arch bridge is one of the first selective bridge style for bridges in mountainous areas,usually using symmetrical structure.There are few engineering examples of long-span asymmetric deck high-speed railway arch bridge,and some key technical parameters of structural design need to be studied.Youshui Bridge on Zhangjiajie-Jishou-Huaihua High-speed Railway is an asymmetric concrete-filled steel tube arch bridge across the Youshui River with 292 m main span.The main arch is composed of two arch ribs,each of which is a truss composed of two large steel pipes of 1500 mm inner diameter and a connecting system.In this bridge,steel column is used as arch column,rigid frame continuous beam+composite beam system is used for superstructure,and weather resistant steel is used for arch rib structure and steel column.The arch rib is assembled by buckle hanging method,the rigid frame concrete beam is poured by hanging basket cantilever,the steel beam is hoisted by whole section,and the bridge deck is prefabricated and installed.In order to study the bridge structure mechanical characteristics and verify the rationality and safety,the stiffness,strength,stability and other indicators of the bridge structure are analyzed by finite element method.The results show that the asymmetric arch bridge can better adapt to the topographical conditions of the bridge site,reduce the bridge span,and have better economy.The bridge structure is safe and reliable with all indexes meeting the requirements of the code.