关键词: 桥梁工程, 扩展有限元, 不连续伽辽金扩展有限元, 正交异性钢桥面板, 疲劳裂纹扩展, 横隔板弧形开孔

Abstract: In order to study the cause of crack occurred at the orthotropic steel bridge deck test model of a long span flat steel box girder，the 3-D segment model was established and calculated by extended finite element method(XFEM) on the basis of the experiment model，and the crack propagation simulation was carried out by the discontinuous Galerkin finite element method(DG-XFEM).The results show that the places near the weld tip of connection of U rib and the curved opening are the high stress zones.This high stresses superimposed on such unfavorable factors as stress concentration caused by geometrical discontinuity，weld defects and built-in stresses make the places near the connection of U rib and the curved opening as the most sensitive sites of fatigue，that is fatigue crack producing area.The initial stage of crack growth is perpendicular to the principal stress isocline and extends along the direction of the maximum principal stress.The position，propagation path and length of the crack are in good agreement with the test results，which is consistent with the position and shape of the cracks in the actual bridge，and is also consistent with the basic theory of crack propagation.

Key words: bridge engineering, extended finite element method(XFEM), discontinuous Galerkin extended finite element method(DG-XFEM), orthotropic steel bridge deck, fatigue crack extension, curved opening of diaphragm