【摘要】 为了分析移动模架施工的PC连续箱梁悬臂端底板裂缝产生的原因及其影响因素,以在建某大桥(4×55m四跨一联PC连续箱梁桥)为工程背景,采用通用有限元软件ABAQUS建立悬臂段预应力混凝土箱梁空间有限元模型,对各荷载作用下的结构空间应力进行分析,并对底板横向应力影响参数进行了敏感性分析。结果表明:底板混凝土开裂的主要原因为箱梁悬臂段集中张拉纵向预应力引起的较大横向应力;底板厚度和底板预应力横向位置对悬臂端底板横向应力影响显著;混凝土泊松比仅对预应力锚点附近的横向应力影响较大;底板锚点力仅对底板中部横向应力的影响较大。建议通过优化纵向预应力布置、局部增加悬臂段底板厚度等措施,以减小底板横向应力。更多还原

【Abstract】 To analyze the causes leading to the cracks in the bottom slab of the cantilever end of the prestressed concrete(PC)continuous box girder constructed by the movable shuttering and the influential factors of the cracks,a bridge(the 4×55-m span PC continuous box girder bridge with each four spans arranged in one unit)being built was taken as an example and the universal finite element software ABAQUS was used to establish the spatial finite element model for the cantilever section of the bridge.The spatial stress of the structure under the different loads was analyzed and the sensitivity analysis of the parameters having influences on the transverse stress in the bottom slab was conducted as well.The results of the analysis indicate that the main cause leading to the cracks in the bottom slab is the great transverse stress caused by the tensioning of the longitudinal prestressing tendons of the cantilever section at one time.The influences of the thickness of the bottom slab and the transverse positions of the prestressing tendons in the slab on the transverse stress in the bottom slab of the cantilever end are significant.The Poisson ratio of the concrete only has considerable influence on the transverse stress close to the anchor points of the prestressing tendons and the anchor point forces in the bottom slab only have influence on the transverse stress in the middle part of the slab.It is hence proposed that the transverse stress in the bottom slab should be reduced by the measures of optimizing the layout of the longitudinal prestressing tendons and locally increasing the thickness of the bottom slab of the cantilever section.更多还原