冻融损伤对混凝土疲劳性能的影响

采用快冻法将混凝土盐冻或水冻至不同损伤程度后进行弯曲疲劳试验。以相对动弹性模量为损伤变量,从损伤的角度分析冻融循环作用对混凝土疲劳寿命的影响,对疲劳试验数据进行威布尔分布检验,建立冻融损伤混凝土的疲劳方程。结果表明,在疲劳荷载相同的情况下,混凝土的真实应力水平随冻融损伤的增加而显著变大,疲劳寿命则急剧降低;在损伤度相同的情况下,盐冻对混凝土疲劳寿命的影响比水冻大;冻融损伤混凝土的疲劳寿命服从两参数威布尔分布,但其离散性要大于未损伤混凝土的离散性;当损伤混凝土与未损伤混凝土的真实应力水平相同时,两者的疲劳寿命基本接近;冻融损伤后混凝土的疲劳寿命与真实应力水平之间的关系可用未损伤混凝土的疲劳方程进行表示。

Influence of freeze-thaw damage on the fatigue life of concrete

Flexural fatigue test was conducted on damaged concrete subjected to water or salt frost with accelerated freeze-thaw cycles.The influence of freeze-thaw damage on concrete fatigue life was analyzed by choosing the relative dynamic modulus of elasticity as the damage index.An equation for fatigue of damaged concrete was put forward after Weibull distribution test of the experimental data.It indicates that freeze-thaw damage had obvious influence on the fatigue life of concrete.In the case of keeping the fatigue load constant,the stress level increased and the fatigue life decreased notably with increasing damage.In the case of keeping the damage degree constant,the influence of salt frost on concrete fatigue life was greater than that of water frost.The fatigue life of frozen concrete followed Weibull distribution with two parameters,but its discreteness was more serious than that of undamaged concrete.With the same stress level,for both damaged and undamaged concrete,the fatigue life was very close.The relationship between the stress level and the fatigue life for damaged concrete could expressed by the fatigue equation of undamaged concrete.