| 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. |
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