【作者】 吕雁；

【导师】 程赫明；

【作者基本信息】 昆明理工大学 ， 工程力学， 2013， 博士

【摘要】 玻璃纤维混凝土(Glass Fiber Reinforced Concrete,简称为GFRC)作为一种新型混凝土材料,由于玻璃纤维的加入,改善了混凝土基体的脆性,提高了抗拉、抗弯、抗冲击及韧性等性能。若将GFRC用于工程实际中可以很好的改善结构和构件的耐疲劳性能。在工程实际中应用得较多、理论研究较为成熟的是钢纤维混凝土,其它纤维混凝土材料的研究还不普遍。玻璃纤维具有优越的物理力学性能,随着玻璃纤维在混凝土工程运用领域的不断扩大,相关理论研究显得尤为重要。混凝土类材料在循环荷载作用下的疲劳强度和变形性能是研究混凝土结构疲劳性能和疲劳强度的基础。为了给GFRC结构的合理设计和正确分析提供重要的试验依据和理论研究参考,论文进行了GFRC弯曲疲劳性能及累积损伤研究,主要试验与理论研究工作包括以下几方面：1、进行了0%、0.6%、0.8%和1%四种纤维率GFRC试件的静载试验和等幅循环荷载试验,研究了玻璃纤维对GFRC各项力学性能(如抗拉强度、抗压强度、抗折强度及抗折弹性模量等)的影响,测量了循环加载下试件的疲劳寿命、应变；对试验结果进行分析,得到了GFRC疲劳应变、疲劳弹性模量和循环应力应变曲线的发展规律及相应经验公式。2、应用统计学理论对GFRC的疲劳寿命进行分析,证明了GFRC的疲劳寿命服从两参数、三参数的Weibull分布,其中三参数Weibull分布更适宜用来描述GFRC弯曲疲劳寿命的分布规律；给出了可用于确定等幅弯曲荷载下GFRC疲劳寿命的S-N曲线、考虑存活率的P-S-N曲线方程。通过方程得到了GFRC的疲劳强度,并与普通混凝土、钢纤维混凝土进行比较,结果说明了GFRC有优越的抗疲劳性能。3、根据GFRC疲劳应变和变形模量随循环次数的发展规律,提出了GFRC弯曲疲劳破坏准则的应变衡量和弹模衡量方法。结合断裂分析中的能量平衡和耗散原理,探讨了GFRC的疲劳内部损伤机理,从而合理地解释了研究获得的疲劳变形规律。4、从连续介质损伤力学、Miner线性累积损伤理论和能量释放理论出发,分别选用由残余塑性应变、最大疲劳应变和循环滞回能表示的损伤变量研究了GFRC的疲劳损伤累积规律,并结合疲劳试验结果确定了模型参数,得到了相应的损伤累积方程。5、运用灰色系统预测理论,在疲劳试验结果的基础上得到了GFRC疲劳强度预测的灰色GM(1,1)模型。在此基础上提出一个模型参数可通过S-N曲线确定,便于工程应用的强度衰减模型,此模型可用于单级循环荷载下GFRC的疲劳寿命估算。以上研究都通过预测值与试验值的比较证明了方法的可行性。更多还原

【Abstract】 Glass Fiber Reinforced Concrete (GFRC) is a kind of new-style material. As intermingled the glass fiber, the properties of GFRC such as brittleness, tensile strength, flexural strength, impactive strength and toughness can be improved. It must improve the anti-fatigue properties of construction and member, if GFRC is used in field of practical engineering. At present, steel fiber reinforced concrete has been used in structural engineering. The researching of other fiber composite materials is not yet widespread, especially for glass fiber. However, the glass fiber has superior physical and mechanical properties. The theory research about GFRC material is very imperative with the extending of GFRC in engineering application confine. The research on fatigue performance and fatigue strength of concrete construction are based on the fatigue strength and deformation performance study of concrete materials. In this dissertation, the flexural fatigue performance and cumulative damage orderliness have been studied based on experimental results. It can give a basilic experimental and academic reference for the reasonable design and scientific analysis about GFRC construction and member. The experimental and theoretic investigation can be listed as follows:1、Through the static and constant amplitude cyclic loading experiments of GFRC specimens with0%、0.6%、0.8%and1%glass fiber volume fraction, the mechanical properties of GFRC(such as compressive strength, tensile strength, elastic modulus) were observed. The developments of specimen strain witll the increase of recurrent times were measured, as well as the fatigue lives of specimens under different stress levels. The development regulation of fatigue strain, fatigue deforming modulus and fatigue stress-strain curve of GFRC were achieved by experimental results analysis.2、According to the statistical analysis of fatigue-life, the study shows the fatigue life of GFRC follows both the two-parameter Weibull distribution and three-parameter Weibull distribution, but three-parameter Weibull distribution is more suitable for expressing the law. The S-N curves which can be used to determine the life of GFRC under constant amplitude fatigue load were obtained. Besides, P-S-N curves with different survival probability were provided. Meanwhile, the fatigue strengths of GFRC were compared with conventional concrete and steel fiber concrete. The results indicate that GFRC has distinguished anti-fatigue property.3、A fatigue equation estimated GFRC flexural fatigue breakage was gained according to the development regulation of fatigue strain and fatigue deforming modulus in terms of cyclic number. Based on energy release and dissipation theory of fracture mechanics, the damage behavior of GFRC under fatigue loading was analyzed, consequently, the observed phenomenon and rules from the experimental results were explained rationally.4、A study on fatigue cumulative damage of GFRC is conducted. The residual strains, maximum strains and cyclic dissipation energy are used to define the fatigue damage. In addition, the law of cumulative damage and its evolution were obtained base on fatigue test data.5、In this part, the method researching on the fatigue strength of GFRC was presented by Gray System Theory. The GM(1,1) model for predicting the fatigue strength or the residual fatigue life of GFRC under constant amplitude cyclic loading was established. The prediction results were compared with experimental results. The results show that this predicting method by Gray system was easy to implement. A residual strength degradation model of GFRC is proposed from the point of view that fatigue is the process during which material strength degrades constantly. The method to determine the parameters of the model from S-N curve is also proposed. It has been verified by the compare with experimental results that these models have good precision, a certain theoreticai significance and value of practical application.更多还原