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针对目前预应力混凝土连续箱梁腹板1/4跨附近开裂现象比较普遍,已严重影响该类桥梁的安全性和耐久性这一问题。分别以重庆石板坡长江大桥和钟祥汉江大桥为例,采用拉-压杆理论,建立拉-压杆模型,研究顶、底板纵向搭接索引起的竖向拉力对预应力混凝土连续箱梁腹板受力状态的影响。在分析顶、底板搭接索反拱石机理的基础上,对预应力混凝土连续箱梁顶、底板纵向搭接索引起的腹板竖向拉力进行了拉-压杆模型分析。研究表明预应力混凝土箱梁顶、底板纵向搭接索可在腹板内引起较大的竖向拉力,并提出了相应的设计注意事项。
In view of the fact that the cracking near the ¼ span of the web of prestressed concrete continuous box girders is relatively common, it has seriously affected the safety and durability of such bridges. Taking Chongqing Shibanpo Changjiang River Bridge and Zhongxiang Hanjiang River Bridge as examples respectively, the tension-compression bar model is established by using the theory of tension-compression bar, and the influence of vertical tension caused by the longitudinal lap joint of roof and floor on the webs of prestressed concrete continuous box girder The impact of the state of stress. Based on the analysis of the mechanism of the anti-arching stone in the top and bottom lap slabs, the vertical tension of the web caused by the longitudinal lapped cable between the top and the bottom of prestressed concrete continuous box girder is analyzed by the pull-strut model. The research shows that the longitudinal lap cable between the top and bottom of prestressed concrete box girder can cause a large vertical tension in the web, and the corresponding design considerations are put forward.