大跨度钢管混凝土劲性骨架箱形拱桥平转施工稳定性研究

大跨度转体拱桥为了实现自重轻,施工方便,往往转出的半跨桥体为开口薄壁板结构,导致桥梁整体在转动及二期荷载施加过程中的稳定问题显得较为突出。为改善其稳定性,半跨转体桥体采用带混凝土底板的小直径钢管混凝土劲性骨架即半跨钢混组合结构的箱形拱空间网架。以四川化成大桥(净跨150 m)为研究对象,建立有限元模型,并对其从施工到成桥过程中的不同阶段进行稳定性分析,找出了结构易发生失稳的薄弱环节,重点分析了二期混凝土浇筑顺序对结构稳定性的影响。通过有限元分析,给出了不同施工阶段的稳定安全系数,得出更安全的施工方案,同时对成桥阶段拱桥的稳定性进行了分析。

Stability Research on Horizontal Rotation Construction of Long-span Box-arch Bridge with Concrete-filled Steel Tube Stiff Skeleton

The half-span arch bridge that turns out is usually an open-walled structure for light self-weight andconvenient construction,causing the stability problem of the whole bridge in the process of rotation construction andsecond-stage loading.In order to improve its stability,the small diameter steel tube concrete stiff skeleton with concretebottom plate,namely the box arch special web frame of the half-span steel-concrete composite structure,was applied forthe half-span rotation part.Sichuan Huacheng bridge(150 m clear span)was taken as the research object.The finiteelement model of the bridge was established,and the stability analysis was carried out at different stages fromconstruction to completion of the bridge.The weak parts prone to instability of the structure were found.The effect of thesecond-stage concrete pouring sequence on the structural stability is focused.Through the finite element research,thestability safety coefficients at different construction stages are given,and the safer construction scheme is obtained.Also,the stability of the arch bridge at completion stage is analyzed.