钢桥面板顶板与纵肋连接疲劳开裂局部加固分析

正交异性钢桥面板纵肋与顶板连接细节处极易产生疲劳裂纹.本文通过精细化有限元模型,分析了栓接角钢加固法和粘贴纤维增强复合材料(Fiber Reinforced Polymer, FRP)型材加固法对钢桥面板疲劳性能的影响.结果表明:采用角钢、FRP型材对顶板与纵肋连接细节的疲劳裂纹进行加固,焊缝裂纹附近热点应力峰值降幅可达56.2%和46.5%;焊缝裂纹尖端附近应力强度因子随着板件整体尺寸的增大而减小;改变板件厚度对应力强度因子结果值影响最大,最高可使其下降约80%,改变板件纵向长度和单肢长度对其有一定影响;随着裂纹的持续扩展,栓接角钢法的加固效果开始下降.建议在监测到构造细节处疲劳裂纹后应尽早加固.

Partial reinforcement effect of fatigue cracks in rib-to-deck joints of orthotropic steel decks

The rib-to-deck joints of orthotropic steel decks are prone to fatique cracks. Through the establishment of finite element model, the influences on the fatigue performance by two approaches, bolting angle steel and pasting FRP profile of orthotropic steel decks, are analyzed. The results show that: the peak value of hot spot stress near weld crack decreases significantly by such two approaches. It can be reduced by 56.2％ by bolting angle steel, and 46.5％ by pasting prefabricated FRP profile. The stress-intensification factor near the tip of the weld crack decreases with the increase of the overall size of the plate, where the most influential factor is the thickness of the plate and the stress-intensification factor can be reduced by about 80％ at most. In addition, the longitudinal length and single limb length of the plate also have certain influence on it. As the crack propagates, the reinforcement effect by bolting angle steel begins to weaken. It is suggested that the reinforcement should be carried out as soon as possible when the fatigue cracks in the longitudinal rib-to-deck joints are monitored.