揭惠铁路跨梅汕高铁特大桥槽箱组合梁设计

Design of U Girders for a Bridge of Jieyang-Huilai Railway Crossing Meizhou-Shantou High-Speed Railway

揭惠铁路跨梅汕高铁特大桥跨径布置为2×72 m,采用半径600 m曲线跨越梅汕高铁,具有曲线半径小、转体跨度大且建筑高度受限等特点。桥型方案比选中,槽形梁桥具有建筑高度低、结构轻巧、造型优美、降噪效果好、断面空间利用率高等优点,为较优方案,但槽形截面为开口截面,抗扭刚度弱,而箱形截面具有良好的抗弯抗扭截面特性,将2种截面组合形成新型结构——槽箱组合梁,在抗扭承载能力要求小的梁段采用实腹式槽形截面,在实腹式槽形截面抗扭承载能力不足的梁段采用整体式箱形截面,该结构融合了槽形截面自重轻、箱形截面抗弯抗扭能力强的优点。揭惠铁路跨梅汕高铁特大桥中墩50 m范围采用箱梁,为保证列车建筑界限,箱内净高8.35 m、净宽7.0 m,剩余95.2 m均为实腹式槽形梁。结构受力分析验证了新型结构的可行性,并在工程实际运用中产生了良好的经济及社会效益。

The bridge of Jieyang-Huilai Railway crossing the Meizhou-Shantou High-speed Railway is a curved bridge that crosses the Meizhou-Shantou High-speed Railway.The bridge has two equal spans of 72 m,following an alignment with a curvature radius of 600 m.During the bridge type selection,the U girder was considered the optimal solution,which could create a lower,light and aesthetically pleasing structure that better balances the small alignment curvature,large structure rotated during construction and height limitation,and additionally causes less noise and allows better utilization rate of spaces.However,the torsional stiffness of the U girder is weak,in this regard,a composite girder that combines the U girder and box girder and takes advantages of the two types of girders is proposed,which owns a light body and exhibits good bending and torsional resistance.For the girder segments with lower torsional resistance demand,the U girders with solid webs are suggested,while for the U girder segments with solid webs do not have sufficient torsional resistance,the integral box girders are suggested.In the bridge of Jieyang-Huilai Railway crossing the Meizhou-Shantou High-speed Railway,box girders are installed in the 50 m-long zone over the central pier,and the remaining 95.2 m-long superstructure consists of U girders with solid webs.A space measuring 8.35 m in net depth and 7.0 m in net width is reserved to ensure the safe distance between the travelling train body and the webs.The analysis of the load bearing behavior of the bridge verifies the applicability of the proposed novel composite girder,and the application on the real bridge creates good economic and social benefits.