【摘要】 基于早年桥梁钢的常规疲劳断裂试验结果 ,比较研究了早年桥梁钢的断裂性能 ;应用概率统计方法分析了早年桥梁钢的疲劳裂纹扩展特性。结果表明 :2 0世纪 5 0年代前生产的铁路桥梁钢材断裂韧性较低 ,低温下 (0℃以下 )裂纹张开位移 (COD)值为 0 0 12～ 0 0 2 9mm ,断裂韧性 (K1C)值为 36 8～ 6 0MPa·m1/ 2 ;其钢材的疲劳裂纹扩展规律相关性较好。运用双随机变量描述了疲劳裂纹扩展过程 ,表现了真实裂纹扩展规律相对Paris公式的偏离程度。给出的疲劳裂纹扩展速率da/dN =7 78× 10 -13 (ΔK) 4 92 (m/周 )可用于现役钢桥的疲劳寿命评估和预测更多还原

【Abstract】 The behavior of fatigue fracture of bridge steel is analysed comparatively,based on available experimental data from previous fatigue tests and some fatigue fracture tests about aged bridge steel.The rate of fatigue crack propagation is studied statistically by considering the fatigue parameters c and n as random variables in Paris′ expression.It is shown that the crack opening displacement(COD)at temperature lower than 0℃ is only 0.012～0.029 mm,correspondingly,the fracture toughness(K 1C)is 36.8～60 MPa·m 1/2 for some bridges′ steel which was made before 1950s,and the rate of crack propagation is bound up with the existing expressions.The curve of the rate of crack propagation expressions da/dN=7.78×10 -13(ΔK) 4.92 (m/cycle)can be applied for the evaluation and prediction on fatigue life of existing steel bridges.更多还原