Abstract: In the practical engineering, box girder web cracking phenomenon is common, and causes of cracking in webs are complex and diverse. The main causes of web cracking of box girder were discussed from the perspective of qualitative and quantitative analysis. It is concluded that: ①the specific causes of web cracking of box girder mainly include concrete shrinkage, temperature effect, radial force caused by bending of prestressing tendons and Poisson effect caused by compressive stress in anchorage zone; among them, the radial force caused by bending of prestressing tendons and Poisson effect caused by compressive stress in anchorage zone are the main causes of box girder web cracking; ②the web cracks caused by these two factors are analyzed by the finite element software ANSYS through engineering examples, and the results show that the web cracking of box girder is easy to occur in the bending section of web prestressing tendons, and its direction is basically perpendicular to the bending prestressing tendons.

Key words: bridge engineering, web cracking, shrinkage and creep of concrete;Poisson effect, finite element analysis

摘要： 基于现实工程中箱梁腹板开裂较为常见现象和腹板开裂成因的复杂性，针对箱梁腹板开裂主要原因，分别从定性和定量角度进行分析探讨。得出如 下结论：①箱梁腹板开裂具体原因主要包括混凝土收缩、温度效应、预应力钢束弯曲引起的径向力以及锚固区压应力带来的泊松效应等，其中由预应力钢 束弯曲引起的径向力和锚固区压应力带来的泊松效应是引起箱梁腹板开裂的主要原因；②利用有限元软件ANSYS通过工程实例对这两个因素引起的腹板开 裂进行了分析，结果显示：箱梁腹板开裂容易发生在腹板预应力束弯起段，且其方向基本垂直于弯起预应力束。

关键词: 桥梁工程, 腹板开裂, 混凝土收缩徐变, 泊松效应, 有限元分析