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

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