柱式塔同向回转斜拉-悬索体系桥梁设计关键技术

Key Design Technique for a Combined Cable-Stayed and Suspension Bridge with Stay Cables Anchored by an Isodirectional Steering System in Columned Tower

安徽某跨江通道方案设计中,提出主桥采用主跨1620 m的斜拉-悬索协作体系桥梁。为解决该体系刚度低、主梁压力间断、边吊杆应力幅大等传统疑问,以及因不能设置辅助墩而引起的边跨刚度小、尾索应力幅高的特殊问题,设计采用单柱式桥塔、空间化悬索构建整体结构,并对结构的合理性、可行性进行理论和计算验证。设计针对体系形成的主要过程,提出边孔悬吊辅助跨构造,采用四索面斜拉索和空间双悬索四索面吊索。借助四索面拉吊融合方式在横向转换的便利、同向回转拉索对不对称布索的支持,使调整在更大空间内进行,实现两种体系更加平顺的融合。采用斜置阻尼约束系统使结构纵、横向动力性能满足规范要求。

In the scheme design of a river crossing in Anhui Province,a combined cable-stayed and suspension structure with a main span of 1620 m for the main bridge is proposed.A series of challenges are usually ahead in construction of such kind of bridge,like the low figidity of the system,discontinuity of compressive force in main girder,large stress amplitude of side hanger cables.And if there is no available condition for auxiliary piers,the rigidity of the side span would be limited,and the stress amplitude of end hanger cables would be high.To address these issues,a spatial suspension structure with mono-columned towers was selected,and the rationality and feasibility of the structure was theoretically calculated and verified.To correspond to the dominant forming process of system,the concept of suspension-assisted side spans was introduced,creating a system with four-plane of stay cables and spatially arranged two suspension cables,together with four-plane hanger cables.The combined four-cable-plane stay cables and hanger cables are beneficial to the system transformation in the transverse direction,and the isodirectionally steered stay cables can compensate the asymmetrical layout of cables,leaving surplus space for adjustment and realizing the smoother merging of the two systems.A kind of inclined damping system is employed to make the longitudinal and transverse dynamic property of the structure meet the code requirements.