PSI - Issue 2_A

Shaowei Hu et al. / Procedia Structural Integrity 2 (2016) 2818–2832 S. Hu et al./ Structural Integrity Procedia 00 (2016) 000–000

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5. Conclusions  The value of initial cracking load ini P and unstable fracture load un P decrease gradually with the increase of specimens’ initial seam height ratio. With the increase of initial seam height ratios, the value of the critical effective crack length c a shows a linearly increasing trend, but the subcritical crack propagation length c a  shows a decrease trend, and the smaller the initial seam height ratio of the specimen, the crack propagation will be more fully and the tenacity of specimen will be better.  The unstable fracture toughness un IC K and the cohesive toughness c IC K are affected by initial seam height ratios, decrease with initial seam height ratios increasing, and the initial fracture toughness ini IC K is independent of it that could be treated as material constant. When calculating the initial fracture toughness ini IC K , the fracture toughness calculation model in this paper can eliminate the errors caused at the moment of determining initial cracking load ini P , which proved its advantage.  For the specimen with a relatively small initial seam height ratio, its fracture features is influenced by maximum tensile-stress failure, and it has a certain shear failure role, which will need larger initial cracking load to make the crack initiation damage occur, and lead to a larger initial fracture toughness. When the specimen is affected by the shear failure role, the splitting tensile failure role will be smaller, which will lead to a inadequate crack propagation, and the subcritical crack propagation length, the cohesive toughness, the unstable fracture toughness will be smaller. Acknowledgements The research described in this paper was financially supported by The National Science Fund for Distinguished Young Scholars (No. 51325904) and The National Natural Science Foundation of China (No. 51279111). Thanks for the helps. Kaplan, M. F., 1961. Crack propagation and the fracture of concrete. ACI Journal proceedings 58(11), 591-610. Hillerborg, A., Modéer, M., Petersson, P. E., 1976. Analysis of crack formation and crack growth in concrete by means of fracture mechanics and finite elements. Cement & Concrete Research 6(6), 773-781. Bažant, Z. P., Oh, B. H., 1983. Crack band theory for fracture of concrete. Matériaux et construction 16(3), 155-177. Bazant, Z. P., Kazemi, M. T., 1990. Determination of fracture energy, process zone length and brittleness number from size effect, with application to rock and concrete. International Journal of Fracture 44(2), 111-131. Jenq, Y. S., Shah, S. P., 1985. A Fracture toughness criterion for concrete. Engineering Fracture Mechanics 21(5), 1055-1069. Jenq, Y., Shah, S. P., 1985. Two parameter fracture model for concrete. Journal of engineering mechanics 111(10), 1227-1241. Xu, S. L., Reinhardt, H. W., 1999. Determination of double-Determination of double-K criterion for crack propagation in quasi-brittle fracture Part I: experimental investigation of crack propagation. International Journal of Fracture 98(2), 111-149. Xu, S. L., Reinhardt, H. W., 1999. Determination of double-K criterion for crack propagation in quasi-brittle fracture, Part II: Analytical evaluating and practical measuring methods for three-point bending notched beams. International Journal of Fracture 98(98), 151-177. Xu, S. L., Reinhardt, H. W., 1999. Determination of double- K criterion for crack propagation in quasi-brittle fracture, Part III: Compact tension specimens and wedge splitting specimens. International Journal of Fracture 98(2), 179-193. Abdalla, H. M., Karihaloo, B. L., 2003. Determination of size-independent specific fracture energy of concrete from three-point bend and wedge splitting tests. Magazine of Concrete Research 55(2), 133-141. Kumara, S., Barai, S. V., 2009. Determining double-K fracture parameters of concrete for compact tension and wedge splitting tests using weight function. Engineering Fracture Mechanics 76(7), 935-948. Kumara, S., Barai, S. V., 2009. Equivalence between stress intensity factor and energy approach based fracture parameters of concrete. Engineering Fracture Mechanics 76(9), 1357-1372. Müller, H. S., Bohner, E., Tritthart, J., et al. 2011. Investigations into fracture of carbonated concrete. Magazine of Concrete Research 63(1), 21 30. Bretschneider, N., Slowik, V., Villmann, B., et al. 2011. Boundary effect on the softening curve of concrete. Engineering Fracture Mechanics 78(17), 2896-2906. Zimmermann, T., Lehký, D., 2015. Fracture parameters of concrete C40/50 and C50/60 determined by experimental testing and numerical simulation via inverse analysis. International Journal of Fracture 192(2), 179-189. References