采用A撑的超宽钢箱提篮拱桥整体顶推受力及安全性能研究

Research on the Overall Top Pushing Force and Safety Performance of the Ultra-wide Steel Box Basket Arch Bridge with A-Braces

为研究超宽桥面拱桥顶推过程的受力性能及安全性能,以某主跨150 m的超宽钢箱提篮拱整体顶推为工程背景进行分析,采用梁格理论来建立大桥有限元模型,结合其实际顶推施工方案,研究最不利悬臂状态的横桥向剪力滞效应、A撑作用和吊杆预紧方案。结果表明:梁顶剪力滞效应显著,梁底应力与单梁结果接近,建议可简化梁格模型为双主梁模型,以提高计算效率;A撑可有效提高结构的刚度,但增加A撑数量,对结构刚度的贡献意义不大,建议A撑布置在最不利悬臂根部;吊杆预紧方案满足安全性能要求,但相比A撑方案,需额外进行一轮调索,影响施工进度,且吊杆预紧力分布不均匀,建议拱桥顶推过程优选A撑方案。

To study the stress and safety performance of the ultra-wide bridge deck arch bridge during the top pushing process,an analysis was conducted using the overall top pushing of an ultra-wide steel box basket arch with a main span of 150 meters as the engineering background.The beam grid theory was used to establish a finite element model of the bridge,and combined with its actual top pushing construction plan,the transverse shear lag effect,A-brace effect,and suspension rod pre-tightening scheme in the least favorable cantilever state were studied.The results show that the shear lag effect at the top of the beam is significant,and the stress at the bottom of the beam is close to that of a single beam.It is recommended to simplify the beam lattice model to a double main beam model to improve calculation efficiency.A-braces can effectively improve the stiffness of the structure,but increasing the number of A-braces has little contribution to the stiffness of the structure.It is recommended to arrange A-braces at the most unfavorable cantilever root.The pre-tightening scheme of the suspension rod meets the safety performance requirements,but compared to the A-bracing scheme,an additional round of cable adjustment is required,which affects the construction progress,and the distribution of pre-tightening force of the suspension rod is uneven.It is recommended to choose the A-bracing scheme for the arch bridge jacking process.