Coupled systems mechanics

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Inverse model for pullout determination of steel fibers

  • Received : 2017.07.14
  • Accepted : 2017.08.22
  • Published : 2018.04.25
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Abstract

Fiber-reinforced concrete (FRC) is a material with increasing application in civil engineering. Here it is assumed that the material consists of a great number of rather small fibers embedded into the concrete matrix. It would be advantageous to predict the mechanical properties of FRC using nondestructive testing; unfortunately, many testing methods for concrete are not applicable to FRC. In addition, design methods for FRC are either inaccurate or complicated. In three-point bending tests of FRC prisms, it has been observed that fiber reinforcement does not break but simply pulls out during specimen failure. Following that observation, this work is based on an assumption that the main components of a simple and rather accurate FRC model are mechanical properties of the concrete matrix and fiber pullout force. Properties of the concrete matrix could be determined from measurements on samples taken during concrete production, and fiber pullout force could be measured on samples with individual fibers embedded into concrete. However, there is no clear relationship between measurements on individual samples of concrete matrix with a single fiber and properties of the produced FRC. This work presents an inverse model for FRC that establishes a relation between parameters measured on individual material samples and properties of a structure made of the composite material. However, a deterministic relationship is clearly not possible since only a single beam specimen of 60 cm could easily contain over 100000 fibers. Our inverse model assumes that the probability density function of individual fiber properties is known, and that the global sample load-displacement curve is obtained from the experiment. Thus, each fiber is stochastically characterized and accordingly parameterized. A relationship between fiber parameters and global load-displacement response, the so-called forward model, is established. From the forward model, based on Levenberg-Marquardt procedure, the inverse model is formulated and successfully applied.

Keywords

Acknowledgement

Supported by : Croatian Science Foundation

References

  1. Carvalho, A.J., Raischel, F., Haase, M. and Lind, P. (2011), "Evaluating strong measurement noise in data series with simulated annealing method", J. Phys.: Conf. Ser., 285(1), 012007. https://doi.org/10.1088/1742-6596/285/1/012007
  2. Do, X.N., Ibrahimbegovic, A. and Brancherie, D. (2015a), "Combined hardening and localized failure with softening plasticity in dynamics", Coupled Syst. Mech., 4, 115-136. https://doi.org/10.12989/csm.2015.4.2.115
  3. Do, X.N., Ibrahimbegovic, A. and Brancherie, D. (2015b), "Localized failure in damage dynamics", Coupled Syst. Mech., 4, 211-235. https://doi.org/10.12989/csm.2015.4.3.211
  4. Imamovic, I., Ibrahimbegovic, A., Knopf-Lenoir, C. and Mesic, E. (2015), "Plasticity-damage model parameters identification for structural connections", Coupled Syst. Mech., 4, 337-364. https://doi.org/10.12989/csm.2015.4.4.337
  5. Kalincevic, S. (2016), "Determination of homogeneity of steel fibers in concrete specimens using computational tomography", M.Sc. Dissertation, supervisor Ivica Kozar, University of Rijeka, Rijeka, Croatia.
  6. Kozar, I., Rukavina, T. and Toric Malic, N. (2017), "Similarity of structures based on matrix similarity", Tech. Gazett., 24(1), 239-246.
  7. Mishnaevsky, L. (2011), "Hierarchical composites: Analysis of damage evolution based on fiber bundle model", Compos. Sci. Technol., 71(4), 450-460. https://doi.org/10.1016/j.compscitech.2010.12.017
  8. Ngo, V.M., Ibrahimbegovic, A. and Brancherie, D. (2014), "Stress-resultant model and finite element analysis of reinforced concrete frames under combined mechanical and thermal loads", Coupled Syst. Mech., 3, 111-144. https://doi.org/10.12989/csm.2014.3.1.111
  9. Ozbolt, J. and Ananiev, S. (2003), "Scalar damage model for concrete without explicit evolution law", Proceedings of the EURO-C 2003 Conference on Computational Modelling of Concrete Structures, Swets & Zeitlinger B.V., Lisse.
  10. PTC Mathcad, Mathcad 14 (2007), Electronic Documentation: Mathcad User's Guide.
  11. Raischel, F., Kun, F. and Herrmann, H.J. (2008), "Continuous damage fiber bundle model for strongly disordered materials", Phys. Rev. E, 77, 046102-046111.
  12. Rinne, H. (2010), Location-Scale Distributions, Justus-Liebig-University, Giessen, Germany.
  13. Sampson, W.W. (2009), Modelling Stochastic Fibrous Materials with Mathematica, Springer, London, U.K.
  14. Smolcic, z. and Ozbolt, J. (2017), "Meso scale model for fiber-reinforced-concrete: Microplane based approach", Comput. Concrete, 19(4), 375-385. https://doi.org/10.12989/cac.2017.19.4.375
  15. Wolfram Research, Inc., Mathematica (2015), Wolfram Language and System, Documentation Center, .