大跨度连续钢桁结合梁设计研究

Research on Design of Large Span Continuous Steel Truss Composite Bridge

连续钢桁结合梁设计中,施工步骤、钢混弹模比、预拱度设置等都是影响最终成桥状态结构受力的关键因素。结合郑济铁路跨黄河北大堤(73+139+73)m连续钢桁结合梁的工程实践,重点对以上几个关键因素进行对比分析。研究表明,在钢桁结合梁的设计中,通过合理安排顶落梁、混凝土桥面板与钢桁梁结合、纵横向预应力张拉等主要施工顺序,可以使桥梁结构受力实现最优。应根据结构形式、施工过程等综合选取钢混弹模比(简单取大值不一定保守)。最后,根据结构力学虚功原理,结合自编程序,解决了大跨度连续钢桁梁的预拱度设置问题。

In the design of continuous steel truss composite beam,the key factors affecting the finished bridge state include construction steps,elastic modulus ratio of steel to concrete and pre-camber setting.Based on engineering practice of(73+139+73)m continuous steel truss composite bridge which strides across the Yellow River North Embankment in Zhengzhou-Ji’nan Railway,this paper focuses on comparing and analyzing the above key factors.Research shows that in the design,the construction sequence of the rising and falling girder,the combination of concrete bridge deck and steel truss girder,the prestressing tensioning should be reasonably arranged to optimize the bridge structural force.Elastic modulus ratio of steel to concrete should be selected according to the structure form and construction process(maybe it is not safer to simply select large values).According to the principle of virtual work combined with self-made program,the camber setting of large span continuous steel truss can be conveniently and efficiently solved.