【作者】 易建龙；

【导师】 陈水福；

【作者基本信息】 浙江大学 ， 结构工程， 2005， 硕士

【摘要】 钢管混凝土拱桥具有跨越距离大、承载力高、塑性和韧性好、施工方便、耐火和耐腐蚀性能好等优点，在实际工程中得到了越来越广泛的应用。钢管混凝土拱桥的破坏主要是拱肋的失稳破坏和强度破坏，失稳破坏有拱肋面内失稳和面外失稳破坏。对于大跨度的拱桥，在其达到面内外失稳时结构一般已进入弹塑性的变形范围，此时结构位移也比较大，因此拱桥的面内外稳定性问题是一个材料与几何非线性的双重非线性问题。 本文同时考虑几何和材料的非线性，采用有限元方法分析钢管混凝土拱桥的面内和面外稳定性问题。本文首先建立了钢管混凝土拱肋的更为精细的有限元计算模型，即对钢管、核心混凝土及管内钢筋分别创建有限单元，其中对外围钢管采用4节点平板壳体单元，核心混凝土采用8节点实体单元，钢筋采用两节点拉压杆单元；然后利用完全Lagrnage方法(T.L法)导出了8节点实体单元和4节点平板壳单元的切线刚度矩阵，对最终的非线性方程采用基于荷载增量的Newton-Raphson迭代方法进行求解。应用该有限元模型，首先对一钢管混凝土拱肋试验模型的面内极限承载力进行了计算，计算结果与试验结果以及采用单一梁单元的计算结果作了比较，验证了该方法的有效性；而后又对该拱肋模型进行了面外稳定性分析，获得了前几阶的面内外失稳形态以及在不同量值面外干扰力作用下的失稳极限承载力。在此基础上对一工程实例——义乌篁园桥的单拱肋的面内极限承载力和面外稳定性进行了计算，将面内的挠度计算结果与实测结果作了比较，并着重分析了在侧向水平风荷载共同作用下的拱肋的失稳形态和面内外失稳的顺序。实例计算表明本文的有限元计算模型不仅可以模拟任意截面形状、任意边界条件、任意荷载下的钢管混凝土拱肋，而且与采用统一理论的单一梁单元相比能更精确地求得拱肋的面内外失稳形态和极限承载力。更多还原

【Abstract】 Owing to many advantages such as large-scaling ability, high load capacities, good fireproofing and earthquake resisting behavior and convenience for construction, concrete-filled steel tubular (CFST) arches have been more and more widely used in practical constructions. The fundamental failure modes of CFST arches are loss of stability and loss of material strength, and loss of stability comprises losses of in-plane stability and out-of-plane stability. For long-span CFST arch bridges, when reaching in-plane or out-of-plane buckling state the material in general enters the elastic-plastic deformation range and the resulting displacements are usually large. Therefore the in-plane or out-of-plane stability problem is that of double nonlinearity including material and geometric nonlinearity.In this paper the finite element method is used for analysis of the in-plane and out-of-plane stability problems for CFST arch bridges, considering the material and geometric nonlinearity. A refined finite-element model for division of arch ribs is first established, in which the four-node flat shell element is employed for the outer steel tubes, the eight-node solid element for the inner concrete and set two-node link (bar) elements for the reinforcing steel bars. Then using the total Lagrange (T.L) method the tangent stiffness matrixes for the eight-node solid element and the four-node shell element are derived. The resulting nonlinear algebraic equation set is solved using the step-by-step Newton-Raphson iteration. Using the current finite element model the in-plane ultimate load-capacity analysis for a CFST arch bridge experiment model is first performed. The obtained results are compared with those of the experiment and those using the single beam-element model. This demonstrates the effectiveness of the present analysis method. Then the out-of-plane stability of the above arch model is analyzed. The first four buckling mode shapes and the ultimate load-capacity due to the out-of-plane buckling under the action of different out-of-plane disturbing loads are found. Finally the in-plane ultimate load-capacity and out-of-plane stability for a practical example-Yiwu HuanYuan CFST arch bridge are analyzed. The obtained in-plane deflection is compared with the corresponding site-test result. The buckling mode shapes and the sequence of in-plane and out-of-plane buckling for this arch bridge are in detail discussed. Through the above analysis and discussion it is seen that the present finite-element model not only can be used for simulation of CFST arch ribs with any cross-sectional shapes and any boundary conditions under any loading, but also more accurately find the in-plane and out-of-plane buckling loads compared with the method using a single kind of beam elements.更多还原