研究目的: 为系统地掌握西北地区大温差、峡谷风、高震区共存的复杂建设条件下上承式钢管混凝土拱桥的力学性能,以一座净跨400 m的公路同类型拱桥为例,按照现行设计规范,采用统一模量法建立三维杆系有限元模型,对概率极限状态设计方法要求的静力性能、稳定性、动力特性、抗震性能的组合工况进行全面、系统地分析和计算,为同类型桥梁设计提供参考。
研究结论: (1)温度效应大于汽车荷载效应,拱脚处横风效应突出;(2)双向偏压、偏拉组合受力为单弦杆控制设计状态,拱顶为桁式拱肋承载力的薄弱位置;(3)腹杆、横撑、平联等构件与弦杆构造匹配性较好时,承载力及疲劳性能等易满足受力需求;(4)温度、徐变预拱度比车道荷载大很多;(5)主拱圈在材料、几何、双重非线性下稳定性分别下降了5.5%、11.9%、17.1%;(6)振型相对密集、频率值较小,主振型为面外弯扭振动,具有多方向和多角度耦联性;(7)时程分析结果大于反应谱分析结果,但小于静力工况,拱桥抗震性能好;(8)上承式钢管混凝土拱桥在复杂建设条件下具有良好的受力性能。

Research purposes: To methodically master the mechanical performance of deck type concrete-filled steel tube arch bridge under the complex construction conditions of the coexistence of large temperature difference, canyon wind, and high earthquake areas in northwest China, a highway arch bridge of the same type with a clear span of 400 meters is used as an example. Based on present design specifications, a three-dimensional bar system finite element model is established using the unified modulus approach, and a thorough and methodical investigation and computation of the combined working conditions of the static performance, stability, and dynamic characteristics and seismic performance have been carried out in order to provide guidance for the design of comparable bridges.
Research conclusions: (1)The crosswind effect at the arch foot is prominent, and the temperature effect is greater than the car load effect.(2)The combined force of bi-directional eccentric tension and compression is in the control design state of single chord, and the arch crown is the weak position of the truss arch rib bearing capacity.(3)The fatigue performance and bearing capacity are easily met when the components, such as web members, transverse braces, and horizontal connections, have good matching with the chord structure.(4)The temperature and creep camber to lane loadis much larger.(5)Under material, geometric, and dual nonlinearity, the main arch ring's stability drops by 5.5%, 11.9%, and 17.1%, respectively.(6)The frequency value is low and the vibration mode is rather dense. Out of plane bending torsional vibration, which possesses multidirectional and multiangle coupling features, is the primary vibration mode.(7)The time history analysis results show that arch bridges function well seismically since they are higher than the response spectrum analysis results but lower than the static conditions results.(8)The deck type steel tube concrete arch bridge has a good mechanical performance under complex construction conditions.