高强钢筋应力与应变疲劳特性的试验和理论研究

Experimental and Theoretical Study on Stress-Strain Fatigue Properties of High-Strength Steel Bars

为比较高强钢筋与HRB400钢筋在疲劳特性方面的差异,通过应力疲劳试验,获得HRB600E、HRB500E钢筋的容许应力幅值,分析钢筋直径对容许应力幅的影响;研究高强钢筋在等幅应变疲劳过程中的应力-应变循环特性,给出Coffin-Manson和Hollomon模型的拟合式和三参数疲劳计算式。首次用耗能韧度评价钢筋在应变疲劳过程中(或地震反复作用)消耗地震能量的能力。结果表明:钒-氮微合金化生产的HRB500E钢筋,其低周应变疲劳寿命和循环韧度均优于钒-氮-铌方法生产的HRB500E钢筋;高强度钢筋有利于提高疲劳寿命、容许应力幅值和总耗能韧度等;总耗能韧度与应变幅有关,增加应变幅值,总耗能韧度减小;相同应变幅值,T63E高强钢筋疲劳寿命比HRB400钢筋更长。最终建立总应变幅与强度损失系数、塑性应变范围的关系。

In order to compare the fatigue characteristics of high-strength steel bars with that of HRB400 steel bars, the allowable stress amplitudes of HRB600 E and HRB500 E steel bars were obtained through stress and strain fatigue tests, and the effects of diameters of steel bars and fatigue loading frequencies on the allowable stress amplitudes were analyzed;the stress-strain cycling properties of high-strength steel bars under constant-amplitude strain fatigue were studied and Coffin-Manson and Hollomon formulas and three-parameter fatigue formulas were established. Energy dissipation toughness was used for the first time to evaluate the capability of steel bars to dissipate seismic energy during strain fatigue(or repeated earthquake action). The test showed that the low cycle fatigue life of strain and cycle toughness of HRB500 E steel bars produced by V-N microalloying were better than those of HRB500 E steel bars produced by V-N-N;method;high-strength steel bars were of benefit to improving their fatigue lifes, allowable stress amplitudes and total energy dissipation toughness. The total energy-consuming toughness was related to the strain amplitudes, increasing the strain amplitude decreased the total energy-consuming toughness;the fatigue life of T63 E high strength steel bars was longer than that of HRB400 steel bars under the same strain amplitude. Finally, the relation between the total strain amplitude and the loss coefficient of strength or the plastic strain range was established.