Issue 39

S. Seitl et alii, Frattura ed Integrità Strutturale, 39 (2017) 110-117; DOI: 10.3221/IGF-ESIS.39.12 116 C ONCLUSIONS n this contribution, the effect of the stress ratios on vibrated concrete was numerically studied, based on test results from 3PBT and WST samples. Despite the absence of data for certain stress ratios, the following conclusions can be drawn from this study:  As a general conclusion from the 3PBT’s and the WST’s, it can be stated that both tests can be used to obtain valuable information about the fatigue crack propagation properties of both vibrated concrete and self-compacting concrete. For small stress ratios like 10-70% the 3PBT is more useful since it usually does not require more than 1000 load cycles until the test specimen fails. For higher stress ratios on the other hand, the WST is more useful, since for these higher stress ratios, the 3PBT specimens tend to fail after very few load cycles.  In general, it can be concluded that the crack propagation in vibrated concrete is faster when the specimen is subjected to a higher stress ratio. A higher stress ratio results in a lower number of load cycles until failure and on average in larger values of the Paris’ law parameters m and C . A CKNOWLEDGEMENT he authors acknowledge the support of Czech Sciences foundation project No. 15-07210S and Brno University of Technology Project No. FAST-S-16-3475. The research was conducted in the frame of IPMinfra supported through project No. LM2015069 of MEYS. R EFERENCES [1] ANSYS Inc, ANSYS Parametric Design Language Guide (14.0), ANSYS Inc, Canonsburg, (2011). [2] Bazant, Z.P., Hubler, M.H., Theory of cyclic creep of concrete based on Paris law for fatigue growth of subcritical microcracks, Journal of the Mechanics and Physics of Solids, 63 (2014) 187–200. [3] Bazant, Z.P., Xu, K., Size Effect in Fatigue Fracture of Concrete, ACI Material Journal., 88(4) (1991) 390–399. [4] Bílek, V., Hurta, J., Done, P., Zidek, L. Development of alkali-activated concrete for structures –Mechanical properties and durability, Perspective in Science, 7 (2016) 190–194. DOI: 10.1016/j.pisc.2015.11.031. [5] Brühwiler, E., Wittmann, F., Special Issue Fracture and Damage of Concrete and Rock The wedge splitting test, a new method of performing stable fracture mechanics tests, Engineering Fracture Mechanic, 35(1) (1990) 117–125. [6] Charles, J., Crane F., Furness, J., Selection and Use of Engineering Materials, third ed., Butterworth-Heinemann, Oxford, (1997). [7] Guinea, G.V., Pastor, J.Y., Planas, J., Elices, M., Stress intensity factor, compliance and CMOD for a general three- point-bend beam, International Journal of Fracture, 89(2) (1998) 103–116. [8] Ince, R., Alyamaç, K.E., Determination of fracture parameters (Ksic and CTODc) of plain concrete using three-point bend tests, Indian Journal of Engineering and Materials Sciences, 15 (2008) 14–22. [9] Karihaloo, B.L., Fracture Mechanics and Structural Concrete, first ed., Longman Scientific and Technical Publishers, John Wiley, Hoboken, (1995). [10] Kolluru, S.V., O’neil, E.F., Popovics, J.S., Shah, S.P., Crack Propagation in Flexural Fatigue of Concrete, Journal of Engineering Mechanics., 126(9) (2000) 891–898. [11] Korte, S., Boel, V., De Corte, W., De Schutter, G., Behaviour of fatigue loaded self-compacting concrete compared to vibrated concrete, Structural Concrete, 15(4) (2014) 575–589. [12] Korte, S., Boel, V., De Corte, W., De Schutter, G., Comparative study on the fatigue behaviour of SCC and VC, Key Engineering Materials., 627 (2015) 333–336. [13] Korte, S., Boel, V., De Corte, W., De Schutter, G., Static and fatigue fracture mechanics properties of self-compacting concrete using three-point bending tests and wedge-splitting tests, Construction and Building Materials., 57 (2014) 1– 8. [14] Korte, S., Experimental and Numerical Investigation of the Fracture Behaviour and Fatigue Resistance of Self- Compacting Concrete., Ghent University, Faculty of Engineering and Architecture, Ghent, (2014). I T