铁路T构矮塔斜拉桥设计分析

Design and Analysis of Railway T-frame Cable-stayed Bridge

研究目的:矮塔斜拉桥是一种介于PC连续梁桥和PC斜拉桥之间的具有良好技术经济指标的桥型,但这种桥型在铁路中应用较少。本文以黔张常铁路澧水南源大桥(136+136)m铁路矮塔斜拉桥为例,介绍其设计特点,通过设计分析总结其在铁路桥梁方面的应用优势。研究结论:(1)矮塔斜拉桥受力呈梁式桥特点,斜拉索相当于主梁的体外束,桥塔相当于体外束的转向装置,受力明确,拉索效率高;(2)塔高度对主梁刚度影响不大,但对主梁受力贡献明显,斜拉索对主梁主拉应力作用明显;(3)主梁结构刚度大,拉索的应力幅小,抗疲劳性能较完全斜拉桥有明显改善;(4)对于斜拉体系桥梁,拉索竖向荷载分担率受到人为因素影响,不能以拉索竖向荷载分担率来界定矮塔斜拉桥;(5)在地形、跨度、净高、净宽等特殊限定条件下,矮塔斜拉桥在铁路建设领域具有较大的竞争优势。

Research purposes： The low tower cable -stayed bridge is between PC continuous beam bridge and PC cable - stayed bridges, which has good technical and economical index. But this kind of bridge is rarely applied in railway. This paper took a （ 136 ＋ 136 ） m railway low tower cable - stayed bridge as an example, introduced the design characteristics, and drew some reference conclusions through analysis of the design. Research conclusions： （ 1 ） The stress characteristic of low tower cable - stayed bridge is quite the same as beam bridge. Suspension cable is equivalent to the external prestressed cable of main girder. Bridge tower is equal to the steering equipment of external prestressed cable. The stress of bridge is clear and the cable is efficient. （2） Height of the tower has little effect on stiffness, but contributed significantly to the main beams, and cable has an obvious effect for girder main tensile stress. （3） The structure of the main girder is large, the stress amplitude of cable is small, and the fatigue resistance is improved obviously compared with the full cable - stayed bridge. （g） For cable - stayed bridge, the vertical load sharing rate of cables is influenced by human factors, so low tower cable - stayed bridge cannot be defined by cable vertical load share ratio. （ 5 ） Under some special conditions, low tower cable - stayed bridge has greatcompetitive advantage in the field of railway construction.