斜交钢箱梁桥顶推导梁的稳定性分析

Stability Analysis of Guide Beam in Skew Incremental Launching Construction of Steel Box Girder

为了分析斜交钢箱梁桥顶推导梁的稳定性,以某两跨斜交连续钢箱梁桥的顶推施工为背景,建立钢箱梁及其导梁结构的有限元模型。通过提取非对称支承工况下结构支反力、导梁腹板以及腹板间横向连接系的应力应变,分析导梁受力特征。在分析线弹性屈曲特征值的基础上,模拟导梁局部失稳并提取屈曲变形特征,分析斜交顶推中的导梁稳定性,进一步探讨不同导梁加固方案的优化效果。结果表明:与正交顶推相比,斜交顶推非对称支承工况下导梁两侧变形不协调,且导梁最前端桁架应力水平较高。在桁架-导梁的相互作用下,导梁屈曲特征值较正交顶推时降低约60%,故导梁稳定性分析应考虑桁架影响。采用增加纵、横向加劲肋对导梁结构进行加固,导梁自重仅增加约5%,但可提高导梁结构的屈曲特征值约20%。该加固方式下结构稳定性增强,可为同类型斜交桥顶推中的导梁设计提供参考。

In order to analyze the stability of guide beam in skew incremental launching construction of steel box girder,based on the jacking construction of a twospan skew continuous steel box girder bridge,the finite element model of steel box girder and its guide beam structure is established.The stress characteristics of the guide beam are analyzed by extracting the structural support reaction force,the stress and strain of the guide beam web and the transverse connection system between the webs under asymmetric support conditions.Based on the linear elastic buckling eigenvalue analysis,the local instability of the guide beam is simulated and the buckling deformation characteristics are extracted.The stability of the guide beam in the skew incremental launching construction is analyzed,and the optimization effect of different guide beam reinforcement schemes is further discussed.The results show that compared with the orthogonal incremental launching construction,the deformation on both sides of the guide beam is not coordinated under the condition of asymmetric support,and the stress level of the front truss of the guide beam is higher.Under the interaction of trussguide beam,the buckling eigenvalue of guide beam is about 60%lower than that of orthogonal jacking,so the influence of truss should be considered in the stability analysis of guide beam.The guide beam structure is strengthened by adding longitudinal and transverse stiffeners.The dead weight of the guide beam only increases by nearly 5%,but the buckling eigenvalue of the guide beam structure can be increased by about 20%.The structural stability is enhanced under this reinforcement method,which can provide reference for the design of the guide beam in the incremental launching construction of the same type of skew bridge.