摘要研究目的：贵广铁路思贤窖特大桥主桥为( 58．5 +109．25 +230 +109．25 +58．5) m 四线铁路斜拉桥，为国内首座四线铁路采用两片主桁的大跨度宽桁斜拉桥。主梁采用两片主桁，桁宽 24 m，主桁采用三角形桁式，桥面系采用带边纵梁和水平 K 撑的密横肋体系。本文对宽桁断面、桁式以桥面系构造和动力性能等关键技术进行了研究，为类似工程提供参考。
研究结论：四线铁路宽桁斜拉桥，四线横梁跨度大，梁跨中、端部弯矩巨大，传递给主桁的面外弯矩较大。研究表明: 无吊杆无竖向 K 撑横断面的三角形主桁桁式，有效地减小横梁跨度，同时每个下弦节点处的两根腹杆共同承受面外较大弯矩。带水平 K 撑和边纵梁的桥面系，通过改变力的传力途径，使主桁只受节点力，改善了横梁和主桁的受力。通过对宽桁断面、桁式以及对带边纵梁和水平 K 撑密横肋体系桥面系的创新性研究，成功地解决了四线铁路宽桁斜拉桥设计中的技术难题。
Abstract：Research purposes:The main bridge of Sixianjiao Bridge of Guiyang－Guangzhou Railway is a 58.5 +109.25 + 230 + 109.25 + 58.5m four tracks railway cable－stayed bridge and it is the first time for the four tracks railway bridge in China to adopt two main truss large span wild－trussed cable－stayed bridge．Two main trusses with width of 24m and triangle truss style are used for the main beam．The K－bar bracing and longitude beams system is used for the deck system．The innovative study is done on the key technologies of the wide truss section，truss type and dense cross rib system with side longitudinal beam and horizontal K brace for providing the reference to the similar works．
Research conclusions:This four tracks railway wide－trussed cable－stayed bridge is featured with the large span of the cross beam for four tracks，the large bending moment of the end and middle parts of the span and the large bending movement transmitted to the outside of main truss surface．The research shows application of the trilateral truss without tie or vertical K brace can effectively reduce the span of the small cross beam and the outside bending moment can be born by two web nodals at the each lower chord point． Application of the deck system with horizontal K brace and longitudinal beam on the edge deck can improve the loading on the cross beam and main truss by changing load transfer channel to make main truss only bearing nodal load．Through doing the innovative research on the cross section of the wide truss，main truss style and the deck system with horizontal K brace and longitudinal beam on the edge deck，the difficult technical problem in design of the four tracks railway wild－trussed cable－stayed bridge have been solved successfully．
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2011, Vol. 28 
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