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以某大跨度连续箱梁桥梁体顶板加劲腋纵向开裂为背景,建立考虑悬臂施工和成桥运营阶段的大桥三维实体有限元模型,分析了横向预应力张拉、挂篮前移、施工不平衡堆载、重车偏载、梯度温度等不同荷载工况对箱室顶板加腋处横向应力分布的影响。结果表明,施工/运营阶段最大组合应力接近混凝土抗拉强度标准值,对大悬臂箱梁,横向预应力张拉是引起梁体纵向裂缝的主要原因。
Based on the longitudinal crack of axillary longitudinal stiffening of the roof of a long span continuous box girder bridge, a three-dimensional finite element model of the bridge considering the cantilever construction and the bridge operation phase is established. The transverse prestressing tension, hanging basket forward and unbalanced construction are analyzed The influence of different loading conditions, such as stack loading, partial load of heavy truck and gradient temperature, on the transverse stress distribution in the armpits of the roof of chamber. The results show that the maximum combined stress of construction / operation stage is close to the standard value of tensile strength of concrete, and the main reason of the longitudinal crack of the beam body is the tensioning of the large cantilever box beam and transverse prestress.