钢筋蚀坑对其疲劳断裂特性的影响

Effect of Corrosion Pits on Fatigue and Fracture Properties of Steel Bars

关键词:  降载勾线法  蚀坑  疲劳裂纹扩展  FRANC3D  数值分析  疲劳寿命

Key words:  beach marking method  corrosion pit  fatigue crack growth  FRANC3D  numerical analysis  fatigue life

摘要:

基于降载勾线法，对人工钻孔模拟蚀坑的3根HPB300钢筋试件开展了疲劳裂纹扩展试验，并结合FRANC3D软件对钢筋疲劳裂纹扩展规律进行了数值分析.在此基础上，以不同应力幅值对12种尺寸的半椭圆形蚀坑钢筋模型的裂纹扩展过程进行了数值分析.结果表明：钢筋裂纹扩展速率前期缓慢增长，后期迅速增大；初始裂纹深度较大的钢筋疲劳寿命明显缩短；初始裂纹深宽比越大的钢筋疲劳寿命越短；应力幅值增大会使缺陷钢筋疲劳寿命缩短，并且初始裂纹深宽比越大的钢筋，其后期裂纹扩展速率增长越快，疲劳寿命缩短越明显.

Abstract:

With artificial drilling pits as simulation of corrosion pits of 3 HPB300steel bars, the fatigue crack growth tests on steel bar specimens were conducted based on beach marking method, and FRANC3D was used to analyze the fatigue crack propagation of steel bars. On this base, the crack growth process of 12semi elliptical pits with different sizes was numerically analyzed with different stress amplitudes. The results show that the crack growth rate grows slowly at first, then increases significantly; the fatigue life of the steel bar with larger initial crack depth is notably lowered; the larger the initial crack depth to width ratio is, the shorter the fatigue life of steel bars is; the fatigue life of the rebar decreases with the increase of stress amplitude, and the larger the initial aspect ratio is, the faster the crack propagation rate increases and the shorter the fatigue life is.