商合杭铁路芜湖长江公铁大桥主桥钢梁设计

商合杭铁路芜湖长江公铁大桥主桥为主跨588m的非对称矮塔斜拉桥。为适应该桥塔矮、索平以及主梁水平轴力大的特点,主梁采用双层桥面箱桁组合结构钢梁,下层为整体钢箱以承担大部分主梁恒载及铁路活载,上层为板桁组合结构以承担剩余恒载及公路活载。主桁采用三角形桁式,桁高15m。斜拉索锚固于下弦杆件,单个钢锚箱内锚固2根最大索力为16 000kN的斜拉索。公路桥面系采用正交异性钢桥面板,铁路桥面系采用封闭式整体钢箱桥面。针对运营状态下在辅助墩处出现支座负反力的情况,采取部分铁路桥面结合梁及箱内压重的措施。钢梁架设采用箱桁同步成桥的方案。

Design of Steel Girder for the Main Bridge of Wuhu Changjiang River Rail-cum-Road Bridge on Shangqiu-Hefei-Hangzhou Railway

The main bridge of Wuhu Changjiang River Rail-cum-Road Bridge of Shangqiu-Hefei-Hangzhou Railway is an asymmetric extradosed cable-stayed bridge with a main span of 588 m.A box-truss composite steel structure is adopted for the main girder to adapt to characteristics of low pylons,small inclined angles of cables,and great horizontal force.The bridge has two layers,the lower deck is made of integral steel box girder and is designed to bear most of the dead load and railway live load,and the upper deck has a plate-truss composite structure and is designed to bear the remaining dead load and highway live load.Triangular truss is used for the main truss,of which the height is 15 m.Stay cables are anchored to the steel anchor boxes at lower chord.Each steel anchor box has two cables anchored with maximum cable force of 16 000 kN.The orthotropic plate is adopted for highway deck,and the integral closed steel box is adopted for railway deck.To avoid negative vertical reaction force at the auxiliary pier under the operation condition,steel-concrete composite bridge deck is adopted for the lower railway deck and concrete blocks are also implemented to balance the vertical force.The scheme that lower deck and the trusses are installed synchronously during erection of steel girder is adopted.