钢桥面板U肋底部非对称弧形缺口的应力特征

Stress characteristic of asymmetric cutouts at the bottom of U-ribs of steel bridge deck

针对钢桥面板检测中U肋底部弧形缺口关于顶板U肋不对称现象,建立对称缺口与2种非对称缺口的有限元模型.首先确定横隔板-U肋相交部位3个构造细节的应力最不利荷载位置,在此基础上研究各细节的应力特征,分析非对称弧形缺口各个构造细节的应力分布和应力组成的影响.结果表明:非对称缺口对各细节应力最不利荷载位置影响较小;非对称缺口影响下缺口偏小侧各细节应力均出现较大增幅;缺口偏小侧弧形缺口周边应力集中现象加剧,应力集中区域扩大并转移至横隔板焊缝端部;非对称缺口增大了横隔板-U肋连接刚度,导致横隔板面外应力占比下降,但部分工况下U肋腹板焊趾处面外作用增大.

Based on the phenomenon that cutouts are asymmetric with respect to the symmetry axis of U-ribs under decks detected in a box girder,three finite element models including symmetrical cutouts and two asymmetrical cutouts models were established.The most critical loading position of three structural details of diaphragm-to-U-ribs joints were determined firstly.Then the stress characteristic of each structural detail was studyed.On the basis,the stress distribution and stress composition of each structural detail on the influence of asymmetric cutouts were investigated.The results showed that the existence of asymmetric cutouts had little influence on the most critical loading position of the detail stress.The stress of each structural detail on smaller cutouts had an obvious increase.The stress concentration area at the edge of cutouts expanded and transferred to the weld end of diaphragm.The stiffness of the local connection between the diaphragm and the U rib at the asymmetric cutouts increased,resulting in an obvious decrease in the proportion of the bending stress.However,the proportion of bending stress at the toe of the U-rib web increased under some load conditions.