PSI - Issue 2_B

Eduardo F. Campello et al. / Procedia Structural Integrity 2 (2016) 2929–2935 Author name / Structural Integrity Procedia 00 (2016) 000–000 7 The relationship between � � � and 2N in Equation (2) lends itself to linearization on a log-log scale and by comparison with the equation representative of the straight line depicted in Figure 3, one can conclude that the fatigue resistance coefficient and exponent are equivalent, respectively, to 7.1 MPa and -0.065. Making use of Equation (1), the value of the ultimate flexural load P u = 2.2 kN leads to a corresponding � � level of approximately 8.8 MPa. Knowing the value of � � and approximating � � � by � � , the fatigue resistance coefficient is estimated at 4.8 MPa, which is in fair agreement with the experimental value mentioned above (7.1 MPa). Finally, it is worth mentioning that results reported by Lee and Barr (2004) on the fatigue behavior of steel fiber reinforced concrete indicated value of the exponent b situated in the range between – 0.0559 and – 0.0575. This is seen to be consistent with the fatigue resistance exponent obtained in the present study for the bamboo reinforced cementitious composite. 4. Conclusions Regarding the results presented herein on the behavior of the bamboo pulp reinforced cement composite, the following conclusions can be drawn:  Fatigue life of the composite can be modeled in terms of the stress amplitude by Manson-Coffin type relationship, with a fatigue resistance exponent of approximately -0.065.  The fatigue resistance coefficient is reduced for cyclic loading conditions involving the presence of tensile mean stress. For a mean stress of 4 MPa , this coefficient is situated at about 7.1 MPa, compared to a theoretical value of about 4.8 MPa.  Small crack formed at the notch root, during casting and curing of notched bend specimens resulted in considerable scatter of the fatigue data, being therefore unfit for possible modeling. References Abu-Lebdeh, T. M., Fini, E., Lumpkin, M., 2012. Flexural and Tensile Characteristics of Micro Fiber-reinforced Very High Strength Concrete Thin Panels. American Journal of Engineering and Applied Science 5, 184-197. Brescansin, J., 2003. Fracture Behavior of Cementitious Matrix Composites Reinforced by Bamboo Pulp. M.Sc. Thesis, Catholic University of Rio de Janeiro, Rio de Janeiro. In Portuguese. Campbell, M. D., Coutts, R. S. P., 1980. Wood Fibre-reinforced Cement Composites. Journal of Materials Science 15, 1962-1970. Campello, E. F., 2006. Fatigue Behavior of Cementitious Composites Reinforced by Bamboo Pulp. M.Sc. Thesis, Catholic University of Rio de Janeiro, Rio de Janeiro. In Portuguese. Dowling, N.E., 1993. Mechanical Behavior of Materials. Prentice-Hall, New Jersey. Kitamura, S., 2006. Experimental Study of the Influence of Fiber Content and Specimen Dimensions on the Split Tensile Strength and its Relationship with the Flexural Strength. M.Sc. Thesis, Fluminense Federal University, Niteroi. In Portuguese. Lee, M. K., Barr, B. I. G., 2004. An Overview of the Fatigue Behavior of Plain and Fiber Reinforced Concrete. Cement and Concrete Composites 26, 299-305. Okafor, F. O., Eze-Uzomaka, O. J., Egbuniwe, N., 1996. The structural properties and optimum mix proportions of palmnut fibre-reinforced mortar composite. Cement and Concrete Research 26, 1045-1055. Pereira, M. V., Fujiyama, R., Darwish, F., Alves, G. T., 2015. On the Strengthening of Cement Mortar by Natural Fibers. Materials Research 18, 177-183. Qian, C. X., Stroeven, P., 2000. Development of Hybrid Polypropylene-steel Fiber-reinforced Concrete. Cement and Concrete Research 30, 63 69. Sales, A. T. C., 2006. Shrinkage, Creep and Fracture of Bamboo Pulp Reinforced Cementitious Composites. D.Sc. Thesis, Catholic University of Rio de Janeiro, Rio de Janeiro. In Portuguese. Silva, F. A., Chawla, N., Toledo Filho, R. D., 2008. Tensile Behavior of High Performance Natural (Sisal) Fibers. Composites Science and Technology 68, 3438-3443. Sivakumar, A., Santhanam, M., 2007. Mechanical Properties of High Strength Concrete Reinforced with Metallic and Non-metallic Fibers. Cement and Concrete Composites 29, 603-608. Toledo Filho, R. D., 1997. Natural Fiber Reinforced Mortar Composites: experimental characterization. D.Sc. Thesis, Catholic University of Rio de Janeiro, Rio de Janeiro.

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