常泰长江大桥主航道桥桥塔设计

Pylon Design for Main Navigational Channel Bridge of Changtai Changjiang River Bridge

常泰长江大桥主航道桥为主跨1 176 m的钢桁梁斜拉桥,采用钢-混混合空间钻石型桥塔。桥塔设计总高352 m,分为上塔柱、中塔柱、下塔柱3个区段。上塔柱采用钢箱-核芯混凝土组合索塔锚固结构,八边形截面。核芯混凝土布置在截面中性轴位置,自上而下厚度均为3.4 m,符合拉-压杆受力模式,压杆由核芯混凝土和受压钢筋构成,拉杆由受拉钢筋和核芯混凝土外壁钢板构成。中、上塔柱交界位置设置榫卯形钢-混结合段,荷载通过核芯混凝土和钢塔外壁板传递至混凝土塔柱。中、下塔柱采用钢筋混凝土结构,正八边形截面。中、下塔柱交界位置设置2道横梁和2道纵梁,横梁和纵梁均为预应力混凝土结构,横梁主要承受横向力、支反力以及碳纤维增强复合材料(CFRP)锚固齿块的作用,纵梁承受纵向力作用。对桥塔进行静、动力及稳定性分析,结果表明其设计指标均满足要求,结构安全可靠。

The main navigational channel bridge of Changtai Changjiang River Bridge is a steel truss girder cable-stayed bridge with a main span of 1 176 m.Rising 352 m,the pylons are spatial diamond-shaped steel-concrete hybrid structures that consists of three zones,specifically the upper,central and lower pylon column zones.The upper column zone accommodates the steel box and core concrete composite anchor structure of octagonal cross-section for stay cables,where the core concrete is placed along the neutral axis of the cross-section,with a constant thickness of 3.4 m over height.The steel box and core concrete composite anchor structure follows the philosophy of strut-and-tie model,in which the strut consists of the core concrete and tensile reinforcing bars,and the tie contains the tensile reinforcing bars and the steel shell encasing the core concrete.A steel-concrete joint section is set between the central and the upper pylon columns,where the steel section and the concrete section are joined via mortise-and-tenon connection details,and loads are transferred trough the core concrete and steel shell to the concrete pylon columns.The central and lower pylon columns are reinforced concrete structures of octagonal cross-section.Two crossbeams and two stringers are set between the central and lower pylon columns,which are all prestressed concrete structures,the crossbeams mainly addresses the transverse force,bearing reaction force and the action of carbon fiber-reinforced polymer(CFRP) anchor wedges,and the stringers accommodates longitudinal force.The results of the static,dynamic and stability analysis indicate that the design parameters of the pylons meet the requirements and the pylon structures are safe and reliable.