Abstract: In order to increase the spanning capacity, shorten the construction period and reduce the cost of the arch bridge, a steel-concrete hybrid arch bridge with concrete structure at the arch foot and steel box structure at the rest was proposed. Based on the 420m span Wanzhou Yangtze River Bridge in Chongqing, the influence of the location of steel-concrete boundary point on the main arch deformation, internal force and the selection of arch axis coefficient was analyzed numerically, by using Ansys parametric analysis method. The research indicates that: the location of the steel-concrete boundary point has a significant effect on the stress and deformation of the arch bridge. When the location of the boundary point exceeds 0.181 times the span of the arch ring, the deformation of the main arch tends to be saddle-shaped. When the boundary point is located in one-fourth of the cross-section of the span, it is necessary to take a larger arch axis coefficient in order to reduce the adverse effect of the dead load pressure line of the arch ring and the deviation of the designed arch axis. The boundary point has significant influence on the bending moment of the arch foot to quarter span and the axial force of the 3/8 span to the arch top section, but relatively small influence on the stress of the arch ring of the whole bridge. The results show that considering the deformation of arch ring, the boundary point of hybrid arch should be located in the span section of 0.125 times arch ring to 0.181 times arch ring.

Key words: bridge engineering, compound arch bridge, boundary point, main arch deformation, arch axis coefficient, internal force of main arch

摘要： 为增大拱桥跨越能力，缩短建设周期，降低工程造价，提出一种拱脚段采用混凝土结构、其余段采用钢箱结构的钢-混混合拱桥形式。以420 m跨 的重庆万州长江大桥为依托，利用Ansys参数化分析方法，对钢-混分界点位置对主拱变形、内力及拱轴系数选取影响进行数值分析。研究发现：钢-混分 界点位置对拱桥受力及变形影响显著，当分界点位置超过0.181倍拱圈跨径后，主拱变形呈马鞍形变化趋势；分界点位于四分之跨截面时，为减小拱圈恒 载压力线与设计拱轴线偏移的不利影响，必须取较大的拱轴系数；分界点对拱脚至四分之跨段弯矩和3/8跨至拱顶段的轴力影响显著，对全桥拱圈应力影 响相对较小。结果表明：考虑拱圈变形有利，混合拱分界点宜位于0.125倍拱圈跨径至0.181倍拱圈跨径段。

关键词: 桥梁工程, 混合拱桥, 分界点, 主拱变形, 拱轴系数, 主拱内力