钢管混凝土拱空间高效双非线性有限元分析

大跨度钢管混凝土空间桁架拱桥的复杂造型使得有限元分析极为特殊,对非线性分析方法的计算精度和效率提出更高要求。采用共旋坐标法,根据共旋坐标系下应变与消除刚体位移后的变形呈线性关系的特点,利用虚功原理无需迭代就能计算出该坐标系下完全粘结钢管混凝土梁单元考虑材料非线性的切线刚度矩阵,再基于场一致性原则导出结构坐标系下考虑几何与材料双重非线性的切线刚度矩阵,从而建立钢管混凝土拱空间高效非线性分析方法。编制了相应的程序,对钢管混凝土模型拱的面内与面外受力进行了计算分析,结果表明在计算精度和效率上是比较满意的。

SPATIAL EFFICIENT BI-NONLINEAR FINITE ELEMENT ANALYSIS FOR CONCRETE FILLED STEEL TUBULAR ARCH

The structural system of long-span concrete-filled steel tube space truss arch bridge is mostly sophisticated, which challenges the implementation of finite element analysis and raises more rigorous requirements for the calculation accuracy and efficiency of nonlinear analysis method. In this paper, firstly, based on the linear relationship between strain and the deformation with rigid body displacement excluded in co-rotational coordinate system, a tangent stiffness matrix for material nonlinearity of perfectly-bonded concrete-filled steel tube beam element is derived without iterations in co-rotational coordinate system by means of virtual work. Then, according to field consistency, a tangent stiffness matrix in global coordinate system for concrete filled steel tube beam element is developed considering geometric and material nonlinearity. An effective algorithm for spatial nonlinear analysis of concrete-filled steel tube arch considering both material and geometry nonlinearity is also obtained. A corresponding computer program is developed. The analysis of in-plane and out-of-plane loading conditions for concrete-filled steel tube arch model is performed. The results demonstrate that the calculation accuracy and efficiency can satisfy the requirement.