考虑钢-混凝土滑移效应的下承式钢桁结合梁受力特性研究

Analysis of the Through Steel Truss Concrete Composite Bridges Considering Shear-slip Effect between Concrete and Steel Truss

对下承式64 m双线钢桁结合梁,考虑钢梁与混凝土板之间的滑移,采用空间梁、板壳单元建立有限元计算模型,钢梁与混凝土板间的连接根据剪力钉刚度,采用弹性连接模拟,通过二期恒载、混凝土桥面板收缩徐变工况的计算分析,研究下承式钢桁结合梁受力特性。计算结果表明,下承式钢桁结合梁中由于混凝土板与主桁下弦杆共同作用承受纵向拉力,钢梁与混凝土板之间的滑移对桥梁结构内力影响较大,设计计算时不适合采用钢梁与混凝土板刚接或换算截面法,建议根据剪力钉刚度钢梁与混凝土板之间采用弹性连接模拟,不同荷载工况可按结构受力对剪力钉刚度进行适当调整。

A 3D finite element analysis integrated with beam and shell elements is carried out to investigate static behaviour of a two-way through steel truss composite bridge of 64 m in span,considering slip effect at the interface of steel beam and concrete slab,by simulating the elastic shear stud stiffness in the cases of the second dead load in addition of shrinkage and creep in the concrete slab.It is demonstrated that subjecting to the longitudinal tensile forces in the concrete slab and in the lower chord of the main steel truss,shear-slip developed at the interface of steel beam and concrete slab will have substantial influence on the internal forces of the bridge structure,so that the equivalent section method in which the concrete section is transformed into a steel section neglecting shear-slip between the two is not reliable upon,and it is suggested that shear studs be simulated using elastic connection elements,and the connection stiffness of which be determined for the corresponding load cases respectively.