双层桥面钢桁腹PC组合桥梁设计与建造方法

Double-deck steel truss web PC composite bridge design and construction method

深圳大学1#桥主桥采用双层桥面钢桁腹预应力混凝土组合结构。主桥结构采用空间放射性钢管混凝土组合桥墩,提高了主梁无横隔板状态下的抗弯与抗扭性能。钢桁腹采用整体式组合节点,用Twin-PBL键加抗剪栓钉的组合连接方式。全桥采用三向预应力布置,上下桥面板纵横向均设置预应力,保证了结构的整体工作性能,同时形成悬臂组合结构;三角形钢管混凝土桁架拉杆施加预应力,在无体外预应力束状态下,起到了降低拉杆的应力、增强节点的连接、满足主梁抗剪要求等三个方面的作用。主桥采用预制拼装、无模板支架施工建造方法。对主桥结构采用Midas/Civil 2010空间有限元分析程序进行分析的结果表明,空间放射性钢管混凝土组合桥墩、整体式组合节点处于弹性工作状态;主梁第1阶自振频率1.13Hz,结构整体刚度好;第1阶屈曲稳定分析特征值为74.6,结构稳定性好。

The Shenzhen University 1 # bridge adopt the double deck steel truss web prestressed concrete composite structure.The main structure of the space radiation concrete filled steel tubular piers can improve the beam flexure and torsion resisting performance without diaphragm condition.Steel truss web is an integral combination of nodes,using Twin-PBL bonding shear stud combination connection.Full bridge is prestressed by tri-directional steel wires.The upper and lower decks use both longitudinal and transverse prestressing to ensure the overall performance of structure,and a cantilever composite structure is formed;the triangular steel pipe concrete truss chord is prestressed to reduce the tensile bar stress,enhance the node connection,and satisfy the main beam shear demand in the absence of external prestressing.The main bridge is assembled without construction formwork.For the main bridge structure,Midas / Civil 2010 finite element analysis program was used for analysis.The results show that,the space radiation concrete filled steel tubular piers and the monolithic composite node stay in the elastic state;the first order natural frequency of the main beam is 1.13 Hz,the whole structure has good stiffness;the eigenvalue of the first order buckling is 74.6,indicating good structure stability.