装配式钢桁-混凝土组合连续刚构桥的预制桥道板安装过程有限元模拟方法

摘要

To study the mechanical performance for a new type of prefabricated steel truss-concrete composite continuous rigid frame bridge which is proposed by our team, a finite element analysis method is conducted considering the installation process of prefabricated slab.Two accurate finite element models are proposed.Method 1: The elastic connectors are activated between steel truss and prefabricated slabs when the steel truss elements are activated, which can realize the pairs an pairs prefabricated slabs assembled on the deformed steel truss.Only the stiffness value of SDx direction is set for the elastic connectors, which can simulate the slabs obtained the compressive pre stress by itself.After the whole prefabricated slabs are assembled on the steel truss and the longitudinal prestressed tendons are tensioned, the elastic connectors are change for rigid connectors.The slabs and the steel truss combined a composite beam to bear the late load.Method 2:The large stiffness elements are activated between steel truss and prefabricated slabs when the steel truss elements are activated, which can realize the pairs an pairs prefabricated slabs assembled on the deformed steel truss.The rotation and horizontal constraint is released at the top of large stiffness elements, which can simulate the slabs obtained the compressive pre stress by itself.After the whole prefabricated slabs are assembled on the steel truss and the longitudinal prestressed tendons are tensioned, the rotation and horizontal constraint is reworked.The slabs and the steel truss combined a composite beam to bear the late load.Two finite element models are established by using the above two methods respectively which main span is 70 m.The key construction stages are analyzed in simulation.The results show that the two methods are accurately simulated the installation process for the prefabricated slabs.The data are in good agreements, the results of this paper can provide a reference for the similar structures.%为了掌握装配式钢桁-混凝土组合连续刚构桥施工阶段的受力性能,对预制桥道板安装过程进行了精细化有限元建模方法研究.根据该桥型的构造和施工特点,提出了两种不同的模拟方法.方法一为提出在安装钢桁单元时激活钢桁与桥道板之间的弹性连接,以实现预制桥道板单元分批次安装在变形后的钢桁上;且仅设置SDx方向刚度值,以此模拟桥道板独自获得预压应力的状态.待全桥桥道板安装及张拉完成后,再将弹性连接方式更换为刚性连接,使之成为组合梁承受后期荷载.方法二为在安装钢桁单元时激活钢桁与桥道板之间钢臂连接单元以实现预制桥道板单元分批次安装在变形后的钢桁上,且释放钢臂连接单元顶端转动及水平约束,以此模拟桥道板独自获得预压应力的状态.待全桥桥道板安装及张拉完成后,再恢复钢臂连接单元顶端的转动和水平约束,使之成为组合梁承受后期荷载.分别用以上两种方法建立了某主跨70 m依托工程的全桥计算模型,对其关键施工阶段进行了仿真模拟分析.计算结果表明:两种计算方法均能精确的模拟预制桥道板安装过程,且两种方法数据吻合较好,可供同类桥梁参考.