天兴州桥正交异性板焊接部位疲劳性能研究

Research on the Fatigue Performance of the Welded Joint of the Orthotropic Deck on Wuhan Tianxingzhou Bridge

武汉天兴洲桥是特大型公铁两用斜拉桥,其公路桥面采用了正交异性板的构造形成。运用有限元分析软件ANSYS和焊接疲劳试验方法,对正交异性板关键焊接部位(槽型闭口肋嵌补段对接处及闭口肋与横梁焊接处)的疲劳性能进行研究。采用ANSYS建立模型,用公路荷载标准进行桥面板应力分析,确定最不利荷载位置,进而计算得到正交异性板槽型闭口肋嵌补段对接处及闭口肋与横梁焊接处的最大应力幅分别为28.6和39.66 MPa。疲劳试验结果表明,焊缝的焊趾是薄弱环节。由疲劳试验得出的槽型闭口肋嵌补段对接焊缝及闭口肋与横梁或横隔板连接焊缝的疲劳容许应力幅分别为89.31和49.14 MPa,大于有限元计算得到的最大应力幅,说明正交异性板关键部位的疲劳性能符合要求。

Wuhan Tianxingzhou Bridge is the major bridge of combined highway and railway Yangtze Bridge. Orthotropic plate structure is adopted for its highway bridge deck. Finite element software ANSYS and welding fatigue test method are adopted to study the fatigue performance of the key welded joints （trough splice welding and trough crossbeam welding） on the orthotropic deck. An integral model of two spans is built with ANSYS, and the deck stress is analyzed according Technical Standard of Highway Engineering. The most unfavorable load position is determined and then the maximum stress ranges of the key welding positions are obtained, of which the trough splice welding is 28.6 MPa and the trough crossbeam welding is 39.66 MPa. The result of fatigue test shows that the welding toe is the vulnerable spot of the welding joint. The maximum allowable stress range of trough splice welding and trough crossbeam welding obtained from the fatigue test is 89.31 MPa and 49.14 MPa respectively, which are higher than those obtained from the finite element calculation. It shows that the fatigue performance of the key welded joints of the orthotropic deck can meet the requirement.