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从对变高度预应力混凝土箱梁桥跨中合龙段底板位置出现的多种纵向裂缝形态的分类出发,分析了跨中底板在自重和预应力作用下所特有的多重荷载效应,通过对某桥梁的有限元数值模拟对多种纵向裂缝形成的原因进行了验证。结果表明,变高度预应力混凝土箱梁桥跨中合龙段底板纵向裂缝不仅是合龙索径向力与梁体自重作用下的横向框架效应耦合作用导致的,而且合龙索锚固力和梁体自重引起的空间折角效应、合龙索锚固力引起的深梁局部效应也是合龙段底板纵向裂缝形成的重要因素。并进一步对影响合龙段底板横向应力分布的因素进行了参数化分析,提出了控制合龙段底板纵向裂缝出现的设计建议。
Based on the classification of various longitudinal cracks in the mid-span of the span of the prestressed concrete box-girder bridge, the multi-load effect that is unique to the mid-bottom floor under self-weight and prestressing is analyzed. The finite element numerical simulation of a variety of vertical cracks formed on the reasons were verified. The results show that the longitudinal cracks in the bottom plate of the span of the prestressed concrete box girder bridge are not only caused by the coupling effect of the transverse frame effect under the action of the radial force of the coiled cables and the dead weight of the beam body, The effect of deep-beam local effect caused by the anchoring force of co-rope is also an important factor for the formation of longitudinal cracks in the slab section of the cohesion section. The factors affecting the lateral stress distribution in the closure section are further analyzed, and the design suggestions for controlling the longitudinal cracks in the closure section of the closure section are put forward.