玻璃纤维混凝土弯曲疲劳性能及累积损伤研究

发布时间：2018-05-09 22:12

本文选题：玻璃纤维混凝土 + 弯曲疲劳　；参考：《昆明理工大学》2013年博士论文

【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。
[Abstract]:As a new type of concrete material, glass Fiber Reinforced Concrete, (glass) can improve the brittleness of concrete matrix and improve its tensile, flexural, impact and toughness properties. If GFRC is used in engineering practice, the fatigue resistance of structures and components can be improved. Steel fiber reinforced concrete (SFRC) is widely used in engineering practice, and other fiber reinforced concrete materials are not widely studied. Glass fiber has excellent physical and mechanical properties. With the continuous expansion of glass fiber in the field of concrete engineering application, the related theoretical research is particularly important. The fatigue strength and deformation behavior of concrete materials under cyclic loading are the basis of studying the fatigue performance and fatigue strength of concrete structures. In order to provide important experimental basis and theoretical reference for the reasonable design and correct analysis of GFRC structures, the bending fatigue performance and cumulative damage of GFRC are studied in this paper. The main experimental and theoretical research work includes the following aspects: 1. Static load tests and cyclic loading tests were carried out on 0 / 0. 6% and 1% fiber GFRC specimens. The effects of glass fiber on the mechanical properties of GFRC (such as tensile strength, compressive strength, flexural strength and flexural modulus) were studied. The fatigue life and strain of specimens under cyclic loading were measured, and the experimental results were analyzed, and the development law and corresponding empirical formula of fatigue strain, fatigue modulus of elasticity and cyclic stress-strain curve of GFRC were obtained. 2. The fatigue life of GFRC is analyzed by statistical theory, and it is proved that the fatigue life of GFRC is from the Weibull distribution of two parameters and three parameters, and the three-parameter Weibull distribution is more suitable to describe the distribution law of GFRC bending fatigue life; The S-N curve which can be used to determine the fatigue life of GFRC under constant amplitude bending load is given. The P-S-N curve equation considering the survival rate is given. The fatigue strength of GFRC is obtained by the equation and compared with ordinary concrete and steel fiber reinforced concrete. The results show that GFRC has superior fatigue resistance. 3. According to the development rule of GFRC fatigue strain and deformation modulus with cyclic times, the strain and elastic modulus measurement methods of GFRC flexural fatigue failure criterion are proposed. Combined with the principle of energy balance and dissipation in fracture analysis, the internal damage mechanism of fatigue of GFRC is discussed, and the fatigue deformation law obtained by the study is explained reasonably. 4. Based on Miner's linear cumulative damage theory and energy release theory in continuum damage mechanics, the fatigue damage accumulation law of GFRC is studied by selecting the damage variables expressed by residual plastic strain, maximum fatigue strain and cyclic hysteresis energy, respectively. According to the fatigue test results, the model parameters are determined and the corresponding damage accumulation equation is obtained. 5. Based on the results of fatigue tests, the grey GM-1) model for fatigue strength prediction of GFRC is obtained by using the theory of grey system prediction. On this basis, a model parameter can be determined by S-N curve, which is convenient for engineering application. The model can be used to estimate the fatigue life of GFRC under single-stage cyclic load. The feasibility of the method is proved by comparing the predicted value with the experimental value.
【学位授予单位】：昆明理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU528.572

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