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为了给大跨径钢桁梁悬索桥抗疲劳设计提供依据,针对杨泗港长江大桥钢桁梁采用的整体焊接节点,开展了多轴疲劳荷载作用下整体焊接节点的有限元疲劳分析和试验研究。首先通过建立全桥有限元模型,基于英国BS 5400规范和Miner准则,获得了在标准疲劳车作用下全桥最不利整体节点及其各杆件200万次等效疲劳轴力幅;其次建立最不利整体节点空间精细化模型,通过对各轴向杆件施加200万次等效疲劳轴力幅,进行了多轴荷载下整体节点的疲劳性能分析;最后基于相似理论,设计了1∶6的整体焊接节点缩尺模型,进行多轴荷载下的疲劳试验研究。结果表明:位于距主塔297m距离的F34节点为疲劳最不利下弦杆整体节点;F34节点最大Von-Mises应力在78.8~130.6 MPa,小于设计规范的疲劳强度;200万次的模型疲劳加载试验过程中,未发现任何疲劳裂纹产生,各测点的应力值与理论值误差小于7.8%;杨泗港长江大桥钢桁梁整体焊接节点疲劳性能满足设计要求,研究成果对大跨径双层悬索桥抗疲劳设计具有直接的指导作用。
In order to provide the basis for the anti-fatigue design of long-span steel truss girder suspension bridge, finite element fatigue analysis and experimental study of the welded joints under multi-axial fatigue load was carried out in view of the whole welded joints of the steel girder bridge of Yangsi Harbor Yangtze River Bridge. First of all, through the establishment of full-bridge finite element model, based on the British BS 5400 code and Miner’s criterion, under the action of the standard fatigue truck, the most unfavorable overall node of the full bridge and its bar are obtained. Unfavorable overall node space refinement model, the fatigue performance of the whole joint under multi-axial load was analyzed by applying 2 million equivalent fatigue axial force amplitude to each axial rod. Finally, based on the similarity theory, a 1: 6 The overall welded joint scale model, fatigue test under multiaxial load test. The results show that the F34 node located at a distance of 297 m from the main tower is the most unfavorable lower chord monolith node. The maximum Von-Mises stress of the F34 node is 78.8-130.6 MPa, less than the fatigue strength of the design code, and 200 000 times the model fatigue loading test , No fatigue crack was found, and the error between the stress and the theoretical value of each measuring point was less than 7.8%. The fatigue performance of the welded joints of steel truss girders of Yangsigang Yangtze River Bridge met the design requirements. The research results showed that the fatigue resistance of long- Fatigue design has a direct role in guiding.