中文摘要：

钢桁腹杆-劲性骨架混凝土（SRC）弦杆组合拱是一种新型的组合结构型式,结合了劲性骨架施工方便快捷和组合结构能大幅减轻结构自重的优点,有望进一步提高拱桥的跨越能力,具有良好的应用前景。该文以跨径为420 m钢桁腹杆-SRC组合拱桥的试设计为基础,进行了组合拱极限承载力的模型试验,试验结果表明,模型拱没有出现面外失稳破坏,结构呈整体破坏;组合拱沿拱轴线方向塑性变形速度要远大于沿截面高度方向,最后因塑性区域开展过大而丧失承载能力,破坏模式接近于钢管混凝土拱的极值点失稳破坏。而后对影响组合拱受力性能的参数进行有限元分析表明,组合拱极限承载力随着混凝土外包系数的增加而增大;腹杆与弦杆钢管的外径比可以提高组合拱的极限承载能力,但超过一定范围时,提高不显著;钢腹杆布置形式对组合拱极限承载力影响较大。最后建立了组合拱的极限承载力简化计算公式,可为此类新型组合拱结构的应用提供参考。

英文摘要：

The steel truss web-steel reinforced concrete（SRC） composite arch is a novel structure, which combines the advantages of convenient and efficient construction of a stiff skeleton frame and can greatly reduce the self-weight of composite structure action. It is anticipated to increase the spanning capacity of arches and has a good engineering potential. Based on the trial-design of a steel truss web-SRC composite arch bridge of a span of 420 m, experiments were carried out on the mechanical behavior of a steel truss web-SRC composite arch model. The experimental results show that： the arch model appeared entire failure mode rather than an out of plane buckling failure; the rates of plastic deformation of the composite arch along the arch axis were much higher than those along the cross-sectional height; final failure of the arch was due to the excessively expanding of the plastic region; the failure mode was similar to the extreme point buckling failure mode of a concrete filled steel tube（CFST） arch. Finite element analysis was also conducted to simulate the mechanical performance of the composite arch. It is shown that the bearing capacity of the composite arch was increased with the increasing wrapping coefficient of external concrete. The bearing capacity was also enhanced with the increase in the ratio of the outer diameter between the web member and the chord. However, the improvement was insignificant when such ratios exceeded a certain limit. The layout details of the steel web members had a great influence on the bearing capacity of the composite arch as well. Based on the test results and the finite element analysis, a simplified design formulae for the determination of ultimate bearing capacity of the composite arch was proposed.