纵肋与顶板新型双面焊构造细节疲劳性能研究

正交异性钢桥面板疲劳开裂问题突出，其中纵肋与顶板传统单面焊构造细节疲劳开裂危害严重，为提升其疲劳性能，通过引入最新自动化焊接技术发展了纵肋与顶板新型双面焊构造细节。为明确其疲劳性能的关键问题，基于等效结构应力法进行了研究：首先对纵肋与顶板新型双面焊构造细节各疲劳失效模式的等效结构应力影响面进行深入分析，确定了构造细节的主导疲劳失效模式；在此基础上，研究了熔透率和焊缝几何尺寸对其疲劳性能的影响。研究结果表明：在纵向移动轮载作用下，纵肋与顶板新型双面焊构造细节的主导疲劳失效模式为顶板外侧焊趾起裂并沿顶板厚度方向扩展；对于该主导疲劳失效模式和焊趾起裂各疲劳失效模式，熔透率的影响不显著；对焊根起裂各疲劳失效模式而言，熔透率是关键影响因素，随着熔透率的增加焊根起裂各疲劳失效模式的等效结构应力幅值呈降低趋势，当熔透率达到75%时，其等效结构应力幅值均处于较低水平，此时纵肋与顶板新型双面焊构造细节的疲劳性能主要由焊趾起裂的各疲劳失效模式所控制；焊脚尺寸是纵肋与顶板新型双面焊构造细节疲劳抗力的另一关键影响因素，适当增大焊脚尺寸可有效降低焊趾起裂疲劳失效模式的等效结构应力幅值，进而提升焊趾起裂疲劳失效模式的疲劳性能。

Fatigue Performance of Innovative Both-side Welded Rib-to-deck Joints

Fatigue cracking is one of the most critical problems plaguing the orthotropic steel bridge deck (OSD). Conventional rib-to-deck welded joint's fatigue cracking is one of the most serious challenges afflicting OSDs. To improve the fatigue performance of the rib-to-deck welded joint, an innovative both-side welded rib-to-deck joint was developed by introducing the latest automated welding technology. Based on the equivalent structural stress method, the fatigue performance of the innovative both-side welded rib-to-deck joint was researched. The predominant fatigue failure mode of this innovative welded joint was determined by the influence surface of the potential fatigue failure mode. The reasonable welding parameters of this joint, such as the size of the fillet weld height and penetration ratio, were analyzed. The results indicate that the predominant fatigue failure mode of the innovative welded joint is cracking initiated from the external deck toe that propagated through the deck plane. For the predominant fatigue failure mode and fatigue failure mode of cracking initiated from the weld toe, the effect of the penetration rate is found not to be significant. However, for the fatigue failure mode of cracking initiated from the weld root, with an increase in the penetration ratio, the equivalent structural stress range is decreased significantly. While the penetration rate reaches 75%, the stress range of the welded root at the lower level, and the fatigue performance of the innovative welded joint is controlled by the fatigue failure mode of the cracking initiated from the weld toe. The weld height is another key factor that affects the fatigue resistance of the innovative welded joint. The equivalent structural stress range of the weld toe can be effectively reduced by properly increasing the weld height, and consequently, the fatigue performance of weld toe can be improved.