Flexural fatigue behavior of lightweight ferrocement: Experimental investigation & numerical modeling

Flexural fatigue behavior of ferrocement elements is evaluated in this paper. Ferrocement elements were developed by incorporating fly ash cenosphere (FAC) as lightweight filler material in various amounts, PVA fibers as discontinuous reinforcement in the matrix, and galvanized iron welded wire mesh as primary reinforcement. Both single and double layer reinforced ferrocement elements were cast. The developed composites were tested for static flexural strength as well as flexural fatigue strength under three-point flexural loading. The fatigue lives, thus, determined at various stress levels and stress ratios were used develop S-N relationships, and equations have been proposed to predict the flexural fatigue strength of ferrocement. The results suggest that the probabilistic distribution of fatigue life of ferrocement can be modeled by two-parameter Weibull distribution. Thus, the Weibull distribution is further employed to incorporate the failure probabilities into the fatigue life of ferrocement. The fatigue lives corresponding to different failure probabilities have been calculated and the data so obtained have been used to generate Pf-S-N diagrams. The obtained results were also compared with the three - parameter Weibull distribution, modeled by ProFatigue, for probabilistic assessment of experimental fatigue data sets. It is found that FAC is useful in producing structural lightweight ferrocement elements with enhanced ductility and improved flexural fatigue characteristics. Further, two - parameter Weibull model is more accurate, in predicting failure fatigue lives of double layer reinforced ferrocement structural elements, as compared to ProFatigue modeling employing three - parameter Weibull model. For single layer reinforced elements, both models can be used with fair confidence level.