Abstract: In order to solve the complex force behavior problem of the combined beam-arch joints of long-span upper bearing beam-arch composite rigid frame, the ultimate bearing capacity of the combined beam-arch joints was investigated by the nonlinear analysis method of the prestressed reinforced concrete materials, which was based on Abaqus damage plastic constitutive model. The research results indicate that: at the intersection of beam and arch under 18 unfavorable load conditions, the maximum positive bending moment combination of the upper chord beam at the combined joints is the most unfavorable and controlling load case, and the ultimate bearing factor of the combined beam-arch joints under the most unfavorable load condition is 2.012, which shows that the coefficient of ultimate bearing capacity is greater than 1.4 and has certain safety reserves. The failure path of the beam-arch joints is as follows: from the tensile failure of the top chord beam bottom slab concrete, with the increase of load, the failure surface gradually extends to the upper chord web, and finally the upper chord beam structure is broken. A method based on Von-Mises stress similarity tracing was proposed to simulate mechanical boundary conditions of solid elements effectively. The equation to judge the internal force balance of the node was given, the influence factor of internal force balance η was proposed. The corresponding threshold range of the influence factor was given by comparing the data, which quantitatively explained the reason why the internal force state of the local strut system model and the whole model could not be the same.

Key words: bridge engineering, upper bearing beam-arch composite rigid frame, beam-arch joints, ultimate bearing capacity, damaged plasticity, load-displacement curve, influence matrix

摘要： 针对大跨径上承式梁拱组合刚构梁拱交汇节点受力复杂的问题，笔者利用基于Abaqus损伤塑性本构模型展开预应力钢筋混凝土材料非线性分析的方法，对上承式梁拱组合刚构进行了梁拱交汇节点极限承载能力的研究。研究结果表明：18个不利荷载工况中梁拱交汇节点处，上弦梁最大正弯矩组合是最不利且起控制作用的荷载工况，最不利荷载工况下梁拱组合节点极限承载因子为2.012，极限承载因子大于1.4，并有一定的安全储备；梁拱交汇节点的破坏路径为：从上弦梁底板混凝土受拉破坏开始，随着荷载的增大破坏面逐渐扩展至上弦腹板，最终上弦梁结构被拉溃；提出一种基于Von-Mises应力相似追踪的方法，可以有效的模拟实体单元力学边界条件；给出了判断节点内力平衡的计算公式，提出内力平衡影响因子η，并通过数据对比给出了影响因子相应的阈值范围，定量的解释了局部杆系模型与整体模型的内力状态无法相同的原因。

关键词: 桥梁工程, 上承式梁拱组合刚构, 梁拱交汇节点, 极限承载力, 损伤塑性, 荷载位移曲线, 影响矩阵