钢桥面板U肋-盖板构造细节(子系统1)疲劳受力行为研究

Study on the Fatigue Behavior of Rib-to-Deck Welded Joint in Steel Bridge Deck Subsystem 1

正交异性钢桥面板受力行为复杂,基于子系统可以更加有效地分析钢桥面板的疲劳受力行为,以钢桥面板子系统1为研究对象,分析轮载作用面积和轮载作用位置对子系统1疲劳受力行为的影响,在此基础上分析了盖板厚度和U肋厚度对U肋-盖板构造细节处3个弯矩的影响。同时基于等效结构应力法,对子系统1的主导疲劳开裂模式进行研究。研究结果表明:轮载作用面积为600 mm×200 mm且轮载作用在U肋间时,子系统1中U肋-盖板构造细节的受力最不利;子系统1以U肋外侧弯矩Mr大于U肋内侧弯矩Ml的情况为主;子系统1焊根开裂模式的主导疲劳开裂模式均为开裂模式Ⅱ,增大盖板厚度能有效降低焊缝焊根开裂的风险;焊趾开裂模式的主导疲劳开裂模式与盖板和U肋厚度有关,增大盖板厚度能减小开裂模式Ⅰ发生的概率,增大U肋厚度能减小开裂模式Ⅲ发生的概率;在焊根和焊趾的主S-N曲线相同的情况下,子系统1的主导开裂模式为焊趾开裂模式。

The behavior of orthotropic steel bridge deck(OSD)is complex,and the fatigue behavior of OSD can be analyzed more effectively based on subsystems,This paper takes Subsystem 1 as the research object,and the influence of wheel load action area and wheel load action position to the fatigue behavior are analyzed.Further the effects of deck thickness and rib thickness to the three bending moments at the structural details of rib-to-deck welded joints are analyzed.The dominant fatigue cracking mode of Subsystem 1 is determined based on the equivalent structural stress method.The results show that when the action area of wheel load is 600 mm × 200 mm and the wheel load acts between ribs,the behavior of the ribto-deck welded joints is the most unfavorable.Subsystem 1 is dominated by the situation that the bending moment M.outside the rib is greater than the bending moment M,inside the rib.In Subsystem 1,the dominant fatigue cracking mode of weld root cracking mode is cracking mode II.Increasing the thickness of deck can effectively reduce the risk of weld root cracking.The dominant fatigue cracking mode of weld toe cracking mode is related to the thickness of deck and rib.Increasing the thickness of deck can reduce the probability of cracking mode I,and increasing the thickness of rib can reduce the probability of cracking modeⅢ.When the main S-N curves of weld root and weld toe are the same,the dominant cracking mode of Subsystem l is weld toe cracking mode.