PC连续箱梁桥箱梁压应力超限的综合处治

为解决预应力混凝土连续箱梁桥因施工缺陷造成的箱梁压应力超限问题,以某预应力混凝土连续箱梁桥为工程背景,提出了箱内采用活性粉末混凝土(RPC)薄层加固、主跨合龙前在主跨侧箱梁最大悬臂端施加临时压重及减小铺装层厚度的综合处治方法,并以有限元分析结果和现场测试结果验证其适用性。结果表明:处治后箱梁压应力超限处的压应力最大降幅为16.8%,并满足现行相关规范的应力限值要求;RPC加固层与原结构整体工作状态良好,局部区域6cm厚的RPC加固薄层可使箱梁整体刚度提高5.8%;对于压应力降幅最大的截面,RPC加固薄层对压应力降低的贡献达58.7%;RPC可实现加固层的轻薄化,所提出的综合处治措施对解决箱梁压应力超限问题有效、实用。

Comprehensive Treatment on Overstressed Compressive Stress in Prestressed Concrete Continuous Box Girder Bridge

In order to solve the problem of overloading compressive stress in prestressed concrete continuous box girder bridge caused by construction defects, selecting a prestressed concrete continuous box girder bridge as project background, we proposed to take comprehensive treatment measures, such as adopting a thin-layer of reactive powder concrete (RPC) to reinforce in the box, exerting temporary loads at cantilever ends in main span of the bridge before the closure of the main span, and reducing the pavement thickness. Meanwhile, the applicability of the proposed measures was validated by the results of finite element analysis (FEA) and site tests. The results indicate that the compressive stresses at the overloading edges in the box girder after treatment were reduced by a maximum percentage of 16.8% and thus can meet the requirements of the stress limit of current relative design norms;the RPC reinforeced layer can match the original structures in working conditions, and the overall stiffness of the box girder is increased by 5.8% after the 6 cm thick reinforced RPC thin-layer is applied in local regions;the thick RPC reinforced thin layer can lead to decrease in stress by 58.7% for the section with the largest reduction of compressive stress. Therefore, the application of RPC can lighten and thin the reinforcement layer, and the measures proposed in the present study can effectively solve the problem of aforementioned overstressing in box girder.