地震断裂带高铁大跨拱桥钢管拱肋的力学特性与施工技术

徐盐高速铁路徐洪河特大桥位于地震断裂带上,跨度为400 m(100 m+200 m+100 m)的预应力混凝土连续梁拱桥是目前国内同类型桥梁跨度最大的,200 m跨钢管拱肋施工是工程中重要的施工难题。为解决大跨度钢管拱肋施工问题,选取合理的施工方案,并验证其可行性。运用有限元分析软件Midas-Civil,建立拱肋支架法安装各阶段的有限元模型,分析各工况下结构内力和变形。结果显示:对钢管拱肋安装支架进行内力和变形分析,结构最大应力发生在跨中支架的中部,其值为58.9 MPa,结构最大位移发生在中部支架顶端,其值为横桥向8.3mm;分析钢管拱肋吊装各阶段工况结构的内力及变形,结构最大应力发生在两端第一根立柱底部,其值为97.8 MPa,结构最大位移发生在中部支架顶端,其值为横桥向20.7 mm;对支架最高单根立柱进行稳定性验算证实,立柱最大应力发生在立柱底端,其值为11.0 MPa,最大位移发生在立柱顶端,其值为横桥向19.1 mm,允许应力170 MPa、控制变形2H/1 000,各分析结果均满足规范要求。研究表明:200 m跨钢管拱肋采用支架法施工,在施工过程中安装支架强度、刚度及稳定性均满足规范要求,方案可行,且为同类型工程施工提供参考。

Mechanical characteristics and construction technologies of steel tube arch rib of large-span highspeed railway bridge in seismic fault zone

Xuhong River Bridge of Xuzou-Yancheng High-Speed Railway is located on a seismic fault zone,of which the pre-stress concrete continuous girder arch bridge with the span of 400 m( 100 m + 200 m + 100 m) is the largest one within the same type bridges in China and the construction of the steel tube arch rib with the span of 200 m is an important construction problem in the project. In order to solve the problem from the construction of the large-span steel tube arch rib,a reasonable construction scheme is selected and then its feasibility is verified as well. With the finite element analysis software-Midas-Civil,the finite element model for all the stages of installing the arch rib with scaffolding method is established, while the internal force and deformation of the structure are analyzed. The result shows that it is demonstrated that the maximum stress occurs at the mid-part of the mid-span supporting bracket with the value of 58. 9 MPa,while the maximum structural displacement occurs at the top of the mid-part supporting bracket with the value of 20. 7 mm in the transverse direction of bridge. The stability checking calculation made on the highest single column verifies that the maximum stress occurs at the bottom of the column with the value of 11. 0 MPa,while the maximum displacement occurs at the top of the column with the value of 19. 1 mm. 7m in the transverse direction of bridge,for which the allowable stress is 170 MPa and the controlling deformation is 2H /1 000,and then all the analysis results meet the requirements of the specification concerned. The study indicates that the application of scaffolding method to the construction of steel tube arch rib with the span of 200 m can meet the relevant specification requirements on installing strength,rigidity and stability of the supporting bracket during the construction,thus the method is not only feasible,but also provides references for the construction of the similar project.