钢管混凝土拱空间极限承载力高精度分析

采用考虑材料非线性的钢管混凝土拱空间极限承载力计算方法对1个X型双肋拱与1个平行双肋拱进行了空间极限承载力计算。在该方法中，对钢管混凝土拱结构采用纤维单元模型，该模型假定钢管与混凝土完全粘接，钢管对核心混凝土的套箍作用体现在以一维形式表达的核心混凝土的应力-应变关系曲线之中，针对材料非线性分析中单元内各点刚度参差不齐的特点，采用单元内设小元的方法(相当于子结构)，编制了非线性有限元程序，在该程序中，计算模型完全是基于小元层次进行的，比如单元刚度矩阵由小元刚度矩阵凝聚而成，单元节点的残余力由小元节点的残余力构成，故只需改变单元内小元个数这1个参数就可实现对结构的重新划分且极大地降低了非线性方程组的阶数，非常方便且实用。在程序计算结果得到模型试验结果验证的基础上，还对不同的横撑根数对结构空间极限承载力的影响进行了分析。

Precision Analysis on Spatial Limit Bearing Capacity of Concrete-filled Steel Tubular Arch

The special ultimate bearing capacity of an x-type double-rib arch and a parallel double-rib arch was calculated with consideration of material nonlinearity. In the calculation, fiber element model, which assumed that the steel tube and concrete are completely cemented, was used to analyze the concrete-filled steel tubular arch structure. The skein function of steel tube to core concrete was reflected in one dimension strainstress curve of the concrete. For different stiffness of individual points of element in material nonlinearity analysis, a nonlinearity finite limit element program was prepared assuming small element as substructure. In the program, calculation model was based on sub-element. For example, element stiffness matrix was composed of sub-element stiffness matrixes and residual force of element node was composed of residual forces of sub-element nodes. As a result, the structure could be easily re-divided and the order of nonlinear equations be greatly reduced by changing sub-element number only. In addition, the effect of transverse brace number on structure special ultimate bearing capacity was analyzed, based on validation of the program with model test results.