大跨径预应力混凝土部分斜拉桥设计关键技术

KEY TECHNOLOGY FOR DESIGN OF LARGE-SPAN PRESTRESSED CONCRETE PARTIAL CABLE-STAYED BRIDGE

以某大跨径斜拉桥为工程背景,综合考虑地质条件、造价、施工难度、后期保养等因素,对比了预应力混凝土部分斜拉桥、下承式网状系杆拱桥、矮塔混合梁斜拉桥3种桥型方案,最终确定拟建桥梁主桥采用120 m+210 m+120 m的双塔单索面混凝土部分斜拉桥,基于数值模拟方法对施工及运营阶段的静力性能、自振特性、稳定性及地震响应进行了分析。结果表明:施工及运营阶段下主梁内力、变形、稳定承载力均满足设计规范要求;拟建桥梁动力特性复杂、主墩抗弯刚度及主梁抗扭刚度较高,主桥抗风稳定性表现良好;三向地震输入时为主桥地震响应最不利条件,在此工况下,主梁竖向位移、主塔弯矩及基础强度均满足设计规范要求。

Taking a large-span cable-stayed bridge as an engineering case,the prestressed concrete partial cable-stayed bridge,through mesh tied-arch bridge and low tower-beam cable-stayed bridge were compared,considering the geology,cost,construction difficulty,late maintenance and other factors.Finally,the 120 m+210 m+120 m double-tower single-plane concrete partial cable-stayed bridge was adopted as the main bridge,and the static performance,natural vibration,stability and seismic response in construction and operation were analyzed by means of numerical simulation.Results show that the internal force,deformation,stability and bearing capacity of the main beam meets the design specifications during construction and operation,the proposed bridge features complex dynamic characteristics,high flexural stiffness of main piers,high torsional stiffness of main beams,and high wind resistance of the main bridge,the 3D seismic input is the most unfavorable condition for seismic responses of the main bridge,but the vertical displacement of the main beam,bending torque of the main tower and strength of the foundation conform to the design specifications.