低温环境下桥梁钢Q345qD疲劳裂纹扩展行为研究  

EXPERIMENTAL STUDY ON THE FATIGUE CRACK GROWTH BEHAVIOR OF BRIDGE STEEL Q345qD AT LOW TEMPERATURES

作　　者：廖小伟[1] 王元清[1] 石永久[1] 陈宏 LIAO Xiao-wei;WANG Yuan-qing;SHI Yong-jiu;CHEN Hong(Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry,Department of Civil Engineering,Tsinghua University,Beijing 100084,China;Architectural Design and Research Institute of Tsinghua University,Beijing 100084,China)

机构地区：[1]土木工程安全与耐久教育部重点实验室,清华大学土木工程系,北京100084 [2]清华大学建筑设计研究院有限公司,北京100084

出　　处：《工程力学》2018年第10期85-91,共7页Engineering Mechanics

基　　金：国家自然科学基金项目(51378289,51678339)。

摘　　要：为了明确在寒冷地区服役桥梁钢的疲劳裂纹扩展行为,以16 mm厚桥梁钢Q345qD为研究对象,完成了室温和低温下的夏比冲击韧性试验、疲劳裂纹扩展速率试验和疲劳裂纹扩展门槛值试验。结果表明,夏比冲击功和试样断口剪切断面率随温度的降低而减少;在应力比0.1、0.2和0.5条件下,疲劳裂纹扩展速率均随温度降低而变缓,该桥梁钢的疲劳韧-脆转变温度点在-60℃以下;在室温^-60℃,其裂纹扩展速率均对应力比的变化不敏感;应力比0.1条件下的疲劳裂纹扩展门槛值随温度的降低有略微增大的趋势。该批次桥梁钢表现出了良好的抵抗低温疲劳裂纹扩展性能,防止低温脆性破坏成为疲劳设计的重点;试验数据能为钢结构桥梁的进一步抗低温疲劳和防低温冷脆断裂设计提供参考。To explore the fatigue crack growth behavior of bridge steel used in cold regions,a series of experimental studies,including Charpy impact test,fatigue crack growth rate test and fatigue crack growth threshold test,were carried out for bridge steel Q345qD with a plate thickness of 16 mm at room and low temperatures.The results show that the impact energy and percentage shear area reduce as the temperature declines.At stress ratios of 0.1,0.2 and 0.5,the fatigue crack growth rate becomes lower with the declining temperatures,and the fatigue ductile-brittle transition temperature of the bridge steel is below?60℃.The fatigue crack growth rate is insensitive to the variation of the stress ratio at both room temperature and low temperatures.At the stress ratio of 0.1,the fatigue crack growth threshold increases with the reduced temperature.It can be concluded that this batch of bridge steel exhibits good resistant performance to fatigue crack growth at low temperatures,making the prevention of low-temperature brittle fracture become the first consideration.The experimental data obtained can be employed for further study on the fatigue&fracture resistant design and fatigue residual life prediction of fatigue detail for steel bridges in cold and extremely cold regions.

关 键 词：Q345qD桥梁钢 疲劳裂纹扩展 低温 门槛值 韧-脆转变温度 

分 类 号：U448.36[建筑科学—桥梁与隧道工程]