高烈度地震区城际铁路斜拉桥设计研究

Design and Study of Intercity Railway Cable-stayed Bridge in High Intensity Earthquake Area

粤东城际铁路跨南溪河特大桥采用(40+75+280+75+40)m双塔双索面混合梁斜拉桥,半飘浮结构体系,是目前国内已设计的地震烈度最高的铁路斜拉桥之一。通过对梁高、索间距等关键参数研究,获得与同类铁路桥梁相比最低梁高、最大索间距,有效降低梁体自重与地震响应;研究出适用于矮墩斜拉桥抗震体系,通过带剪力销的抗震球型支座与黏滞阻尼器共同作用,实现减震消能并控制地震位移,并将桥塔处纵横向阻尼器合并设计,合理利用黏滞阻尼器防止支座地震作用下的“跳起”现象;为解决下塔柱高度过小、桥塔横梁刚度大导致的结构外形不协调、次内力大、地震响应大的问题,提出一种下横梁-下塔柱一体化设计方案,有效减小了桥塔及其横梁静力及地震力,且结构美观协调;为了解决高烈度震区下,桥塔混凝土上横梁由于地震产生的巨大剪力导致横梁尺寸及配筋率、用钢量过大的问题,创新性提出一种轻型、柔性钢结构上横梁,节约了材料用量,并大幅优化了其在横震作用下的受力性能;通过CFD仿真模拟,对该桥抗风性能进行研究;通过对结构风-车-桥空间耦合振动性能进行研究,结果表明该桥施工及成桥阶段抗风性能均满足规范要求,且能够满足城际铁路无砟轨道对结构安全性和行车舒适性的要求。

The Guangdong East Intercity Railway Cross Nanxi River Extra Large Bridge adopts a(40+75+280+75+40)m double tower double cable plane hybrid beam cable-stayed bridge,which is Semi floating structural system,is currently one of the railway cable-stayed bridges with the highest seismic intensity designed in China.The article studies key parameters such as beam height and cable spacing to obtain the lowest beam height and maximum cable spacing compared to similar railway bridges,effectively reducing the self weight and seismic response of the beam body;An earthquake resistant system suitable for low pier cable-stayed bridges is developed,which utilizes seismic spherical bearings with shear pins and viscous dampers to achieve seismic energy dissipation and control seismic displacement.The longitudinal and transverse dampers at the bridge tower are combined for design,and viscous dampers are used reasonably to prevent the phenomenon of"jumping"under seismic action of the bearings;To solve the problems of inconsistent structural appearance,large secondary internal forces,and large seismic response due to the low height of the lower tower column and the high stiffness of the bridge tower crossbeam,an integrated design scheme of the lower crossbeam and lower tower column has been proposed,which effectively reduces the static and seismic forces of the bridge tower and its crossbeam,and the structural aesthetics are coordinated;In order to solve the problem of excessive size,reinforcement ratio,and steel consumption of bridge tower concrete beams due to the enormous shear force generated by earthquakes in high-intensity earthquake zones,a lightweight and flexible steel structure upper crossbeam has been innovatively proposed,which saves material usage and greatly optimizes its stress performance under lateral seismic action;Through CFD simulation,the wind resistance performance of the bridge was studied;By establishing a spatial coupling vibration analysis model for the vehicle bridge system,research was conducted on the wind vehicle bridge spatial coupling vibration,and the results show that the wind resistance performance of the bridge during construction and completion stages meets the regulatory requirements,and can meet the structural safety and driving comfort requirements for ballastless tracks on intercity railways.