Abstract: The section form of equal width and variable height is mostly adopted in long-span concrete-filled steel tubular arch bridges. Based on the analysis of the design parameters affecting the variable section height in the Ritter formula, a new method for the variable section height design of steel tubular arch was proposed, that is, the section height of arch rib was defined as the ratio of the power of the arch crown height to the cosine of the horizontal inclination of the arch axis, and the power was uniquely determined by the equations of the arch crown height, arch foot height and arch axis. Combined with the ratio of rise to span and arch axis coefficient commonly used in concrete-filled steel tubular arch bridges, the range of power value was given. In order to verify the feasibility of the proposed method in the design of long-span steel tubular arch, the dynamic characteristics and elastic stability analysis of two concrete-filled steel tube arch bridges were carried out. The results show that, compared with the calculation results of design documents and Ritter formula, the concrete-filled steel tubular variable section arch designed by the proposed method has a difference in chord axial force between 1.7% and 7.0%. The difference in dynamic characteristics, elastic stability, and web stress is within 5%. The proposed design method can provide reference for the design of concrete-filled steel tubular arch bridge in the future.

Key words: bridge engineering; variable section design method; concrete-filled steel tubular arch bridge; variable section height; Ritter formula

摘要： 大跨度钢管混凝土拱桥大多采用等宽变高的截面形式。分析了李特公式中影响变截面高度的设计参数，在此基础上提出了钢管拱变截面高度设计的一种新方法：将拱肋截面高度定义为拱顶高度与拱轴水平倾角余弦值的幂次方之比，幂次方由拱顶高度、拱脚高度和拱轴线方程唯一确定。结合钢管混凝土拱桥常用的矢跨比和拱轴系数，给出了幂次方的取值范围。为验证该方法在大跨度钢管拱设计中的可行性，开展了两座钢管混凝土拱桥的动力特性与弹性稳定分析。结果表明，采用该方法设计的钢管混凝土变截面拱，与设计文件和李特公式的计算结果相比，钢管拱弦杆轴力差异在1.7%~7.0%，动力特性、弹性稳定以及腹杆应力差异在5%内。文中提出的设计方法可以为今后钢管混凝土拱桥设计提供参考。

关键词: 桥梁工程；变截面设计方法；钢管混凝土拱桥；变截面高度；李特公式