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通过三点弯曲疲劳试验测试得到了应力水平为0.4,0.5,0.6时90 d龄期普通混凝土和钢纤维聚合物混凝土弯曲疲劳寿命,通过压汞试验试得到了同龄期混凝土的微观孔结构特征参数及孔径分布,分析了钢纤维和聚合物乳液对混凝土疲劳性能的影响规律及作用机理。分析结果表明,循环荷载作用下普通混凝土和钢纤维聚合物混凝土的疲劳寿命符合两参数威布尔分布,相同应力水平下钢纤维聚合物混凝土的疲劳寿命远高于普通混凝土,并建立了失效概率为0.5时混凝土的双对数疲劳方程。弯曲疲劳荷载作用下钢纤维对混凝土疲劳性能改善的机理在于纤维拔出过程中能量耗散,纤维细化了混凝土特征孔隙尺寸,使有害孔隙减少、无害孔隙增加;聚合物乳液对混凝土疲劳性能改善的机理在于增强了钢纤维-水泥石界面黏结性能。
The flexural fatigue life of ordinary concrete and steel fiber reinforced polymer concrete with stress levels of 90, 90, and 90 days were obtained by three-point bending fatigue test. The microscopic pore structure parameters of same age concrete were obtained by mercury intrusion test And pore size distribution, analyzed the influence law and mechanism of steel fiber and polymer emulsion on the fatigue property of concrete. The analysis results show that the fatigue life of ordinary concrete and steel fiber polymer concrete under cyclic load accords with two-parameter Weibull distribution. The fatigue life of steel fiber polymer concrete under the same stress level is much higher than ordinary concrete, and the failure probability is 0.5 when the double logarithmic fatigue equation of concrete. The fatigue mechanism of steel fiber under flexural fatigue load is due to the energy dissipation during the fiber pull-out process. The fibers refine the characteristic pore size of concrete so that the harmful pores decrease and harmless pores increase. The fatigue behavior of concrete The improvement mechanism is to enhance the bond performance of steel fiber-cement interface.