大跨度三塔钢箱-桁结合梁斜拉桥受力性能研究

蒙华铁路洞庭湖特大桥主桥为大跨度三塔双索面钢箱-桁结合梁斜拉桥,主梁首次采用适合重载铁路大跨度三塔斜拉桥受力特点的钢箱-桁组合新结构,钢梁制造安装精度要求高,施工技术难度大。通过研究钢箱-桁组合结构下主桁、主塔、斜拉索和桥面系的刚度,提出增设中塔稳定索来提高三塔双主跨竖向刚度。中塔稳定索面积为241 cm2能使挠度降低20%,中塔塔顶水平位移降低41%,塔底弯矩降低64%。

Research on Mechanical Performance of Long Span Three-tower Steel Box-Truss Composite Girder Cable-stayed Bridge

The main bridge of Dongting Lake super large bridge on Mengxi-Huazhong railway is a long span threetower double cable plane steel box-truss composite girder cable-stayed bridge.For the first time,the main girder adoptsthe steel box-truss composite structure which is suitable for the mechanical characteristics of the long span three-towercable-stayed bridge on heavy haul railway.This structure needs high accuracy during manufacturing and installation ofsteel girder.The construction technology is difficult.By studying the stiffness of main truss,main tower,stay cable andbridge deck system under the new steel box-truss composite structure,it is proposed to increase the vertical stiffness ofthree towers and double main spans by adding middle tower stable cable.The area of stable cable in the middle tower is241 cm2,which can reduce the deflection by 20%,the horizontal displacement at the top of the middle tower by 41%,and the bending moment at the bottom of the tower by 64%.