伦洲大桥主桥结构设计

Structural Design of Main Bridge of Lunzhou Bridge

伦洲大桥主桥为100m+2×170m+100m空腹式连续梁-刚构组合体系。主梁采用单箱双室截面,主梁上、下弦汇合段采用柔性中板方案;下弦设置顶板束,梁段根部下弦设置腹板下弯束,顶板悬臂浇筑束两两错开布置;上、下弦汇合前施加顶推力并设置临时固结;主墩为实体墩,中主墩固结,边主墩释放,边主墩横向设3排支座,墩顶设临时固结块。0号块、边跨现浇段及合龙段采用支架现浇,其他节段采用挂篮悬臂浇筑。分别采用MIDAS Civil 2010、ANSYS 10.0软件进行主桥总体及局部应力分析,计算结果表明:伦洲大桥各项指标均能满足规范要求,且有一定的安全储备。

The main bridge of the Lunzhou Bridge is a prestressed concrete hybrid system of open-web continuous girder and rigid-frame with span arrangement 100 m＋ 2 ×170 m＋100 m. The main girder of the bridge is of twin-cell single-box section and at the meeting section of the upper and lower chords of the girder, the flexible central partition wall is employed. In the lower chord, the top slab prestressing tendons are set and in the lower chord of the root part of the girder, the web draped tendons are set. The tendons for the top slab to be cantileveredly cast are staggered in each two tendons. Before the upper and lower chords meet, the pushing force is ap- plied and the temporary rigid fixity is made. The main piers of the bridge are the solid ones, of which the pier in the middle is rigidly fixed and the side piers will release stress. On the top of each side main pier, 3 arrays of bearings are arranged in transverse direction and the temporary rigid fixing blocks are arranged as well. The segments No. 0, the cast-in-situ segments of side spans and closure segments are constructed on scaffoldings while the rests of the segments are cantileveredly constructed, using the form travelers. The software MIDAS Civil 2010 and AN- SYS 10.0 are respectively employed to analyze the global and local stress of the main bridge and the results of the calculation and analysis indicate that all indices of the bridge can satisfy the re- quirements in the codes and have certain safety margin.