高速铁路四线大跨钢桁斜拉桥主桁研究

目前四线铁路钢桁梁多采用三主桁型式,采用双主桁的四线铁路桥跨度多在200 m左右。当四线铁路钢桁梁采用双主桁时能适应最小线间距要求,减小主桁横向总宽度,并降低主桥和引桥的工程规模及邻近隧站工程量,因此研究双主桁大跨度钢桁斜拉桥在工程上具有重要意义。结合某高速铁路四线大跨钢桁斜拉桥主桁横断面布置及桁梁主要构造尺寸,从结构受力、技术经济指标、不同桁宽所引起的引桥规模等方面研究三片桁与两片桁的主要差别,合理推断出四线高速铁路钢桁梁最小桁宽。同时从主桁腹杆承受较大面外弯矩及用钢量等方面比较四线主桁腹杆采用三角桁与N形桁的区别。最终确定主桁梁采用桁宽24.3 m的双主桁、腹杆为三角形桁式的钢桁架。研究结果表明:四线双主桁钢桁斜拉桥应用到500 m左右大跨度桥中在技术和经济上是可行的。

Research on Main Truss of Long-span Steel Truss Cable-stayed Bridge in Four-line High-speed Railway

Steel truss girder in four-line railway is generally designed with three main trusses at present and the span is generally about 200 m when two main trusses are used. Steel truss girder should be so designed as to adapt to the requirements of minimum line spacing,reduction of total transverse width,lowering of engineering scale of main span,approach span and nearby tunnel and station when two main trusses are in place. Therefore,the research on long-span steel truss cable-stayed bridge with two main trusses bears great significance in engineering. With the consideration of cross section layout and size of the main truss in a long-span steel truss cable-stayed bridge in high-speed railway,the major differences of two-truss and three-truss are studied in terms of structural performance,technical and economic index and project scales of approach spans corresponding to different truss widths,based on which the minimum width of steel truss girder in four-line railway is inferred reasonably. The differences between the triangular truss and the N truss are compared in view of the out-of-plane bending moment of the web member and the steel consumption. Steel truss with 24. 3 m width double-truss and triangular web member is employed as the main truss girder. The results show that the steel truss cable-stayed bridge with two main trusses is applicable technically and economically in a bridge with span around 500 m in four-line railway.