Q345qD桥梁钢疲劳裂纹扩展速率试验研究  

Experimental Study on Fatigue Crack Growth Rate of Q345qD Bridge Steel

作　　者：宗亮[1] 施刚[1] 王元清[1] 廖小伟[1] 

机构地区：[1]清华大学土木工程系,北京100084

出　　处：《中国铁道科学》2015年第3期37-44,共8页China Railway Science

基　　金：铁道部科技研究开发计划项目(2012G011-E)

摘　　要：为采用线弹性断裂力学方法对既有铁路钢桥进行疲劳评估,利用紧凑拉伸试样、基于柔度法的测量手段,对6.1,10.0和23.5mm厚的我国应用最广泛的Q345qD桥梁钢进行疲劳裂纹扩展速率试验,分别采用单试件数据点和成组（相同材料、厚度和应力比）数据点拟合,得到不同厚度、不同应力比下试件的疲劳裂纹扩展速率参数。试验结果表明：在通常的应力强度因子幅值范围（10~70 MPa·m1/2）内,基于单试件数据点拟合参数得到的疲劳裂纹扩展速率明显高于基于成组数据点拟合参数得到的裂纹扩展速率;Q345qD桥梁钢的疲劳裂纹扩展速率随应力比增加而增加,当应力比从0.1增加到0.5时,本批次钢材的疲劳裂纹扩展速率增幅为7%~25%,但随板厚增加的变化并不显著;本批次Q345qD桥梁钢的疲劳裂纹扩展性能优于HPS485W和14MnNbq桥梁钢及BS7910标准中给出的通用钢材疲劳裂纹扩展性能。The experimental study on the fatigue crack growth rate of the most widely used Q345 qD bridge steel with the thickness of 6.1,10.0and 23.5mm were performed with compact tension specimens and the measurement technique based on flexibility method,aiming to facilitate the fatigue assessment of existing railway steel bridges based on linear elastic fracture mechanics.By fitting the data points of single specimen and those of group specimens with the same material,stress ratio and thickness respectively,the parameters related to the fatigue crack growth rate of the specimens with different thickness and stress ratio were obtained.Test results show that the fatigue crack growth rate based on each single specimen data is significantly higher than that based on group specimens data handling in terms of normal stress intensity range（10~70 MPa·m1/2）.The fatigue crack growth rate of Q345 qD bridge steel increases as the stress ratio increases.With the increase of the stress ratio from 0.1to 0.5,the increment in the fatigue crack growth rate for the bridge steel of this batch is from 7%to 25%.However,the fatigue crack growth rate is not significantly affected by plate thickness.The fatigue crack growth rate of this batch Q345 qD bridge steel is superior to that of HPS485 Wand 14MnNbq bridge steel defined in BS7910 standard for the fatigue crack growth performance of the general steel.

关 键 词：桥梁钢 应力强度因子 应力比 疲劳裂纹扩展速率 

分 类 号：U448.36[建筑科学—桥梁与隧道工程]