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Chapter 4. Bond behavior of fibers in cementitious materials: a unifiedformulation• Thus, a more complex, but more accurate fracture energy-based softening modelhas also been presented and the key aspects of the numerical procedure neededfor handling such a relationship are outlined;• The solutions obtained by considering both models have been validated againstexperimental results obtained on pull-out tests of smooth and straight steel fibers,currently available in the scientific literature;• Both models demonstrate the capability of the proposed unified formulation tocapture the key aspects of the complete pull-out response of fibers embedded incementitious matrices and taking into account the possible influence of relevantparameters, such as bond length and fiber diameter.As a final comment, it is worth highlighting that the proposed formulation can bestraightforwardly employed in numerical models aimed at simulating the behaviorof FRCC through a discrete-crack approach, as such model (i.e., meso-mechanicalone) explicitly simulates the bond-slip response of fibers embedded in cementitiousmatrices. The adoption of the presented formulation within the framework of generalmeso-mechanical models of FRCC is, at the same time, the key motivation and themost relevant development of this chapter.Despite the weaknesses described for the above mentioned bilinear relationship, numericalsimulations are generally in good agreement with the corresponding experimentaldata. Moreover, the mesoscale formulation proposed by means of the zerothicknessinterface formulation presented in Chapter 3 and then validated in the followingChapters (5 and 6), actually considers the bilinear proposal for the fiber debondinginto the complete formulation for FRCC failure analysis.92
5 Model performance and numericalpredictionsThis chapter proposes a preliminary calibration and some applications of the proposedinterface model for FRCC failure analysis. Numerical simulations against availableexperimental test data are presented for investigating the soundness and capabilitiesof the proposed methodology.5.1 Numerical analysesFor the calibration purpose, experimental results on Steel Fiber-Reinforced Concrete(SFRC) specimens, tested in pure tension, are considered while for the evaluation ofmodel predictions, failure processes under mixed-modes of fracture, in plain and SFRCnotched specimens, are taken into account.5.1.1 Calibration of the interface model for SFRCIn this section, the interface model is calibrated by using experimental results performedon SFRC specimens tested in pure traction. One interface element, with differentfiber contents, connecting two 4-node plane stress isoparametric elements isemployed for this purpose. Particularly, the basic element patch, shown in Figure 5.1,is considered.The number of fibers per interface is evaluated by means of the expression proposedby Krenchel [1975]n f = α ⃗ Nρ fA fA i (5.1)93
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Dottorato di Ricercain Ingegneria d
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AcknowledgementsI would like to exp
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Abstractinclusion of fibers and the
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ContentsAcknowledgementsAbstractTab
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Contents8.6.1 Tensile tests . . . .
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List of Figures2.1 Fine and coarse
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List of Figures4.16 Pull-out simula
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List of Figures6.14 Crack paths of
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List of Tables2.1 Mix design per cu
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Chapter 1. Introduction1.1.1 Fiber
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Chapter 1. Introductionthe fiber ad
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Chapter 1. Introductionand mechanic
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Chapter 1. Introduction[Vrech and E
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Chapter 1. IntroductionDespite the
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Chapter 1. Introduction(Figure 1.4)
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Chapter 1. IntroductionFigure 1.8:
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Chapter 1. Introductionfor structur
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Chapter 1. Introductioncracking beh
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Chapter 1. Introduction• "c" if 0
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Chapter 1. Introductionsumed due to
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Chapter 1. Introductionaleatoric na
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Chapter 1. IntroductionFigure 1.13:
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Chapter 1. IntroductionElement Meth
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Chapter 2. Experimental characteriz
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Page 68 and 69: Chapter 2. Experimental characteriz
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Page 93 and 94: 4 Bond behavior of fibers in cement
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Page 167 and 168: 7 Cracked hinge numerical modelfor
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7.1. Basic assumptionsSection at no
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7.1. Basic assumptions1997, Stankow
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7.2. Bond-slip bridging of fibers o
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7.4. Numerical predictionsvertical
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7.5. Closing remarksthe experimenta
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Chapter 8. Elasto-plastic microplan
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Chapter 9. Conclusionsof first-crac
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Chapter 9. Conclusionsfibers in con
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Chapter 9. Conclusions9.6 Future re
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BibliographyN. Banthia and N. Nanda
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BibliographyM. Butler, V. Mechtcher
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BibliographyCUR. Bepaling van de Bu
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BibliographyEN-12390-3. Testing of
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BibliographyT. Guttema. Ein Beitrag
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BibliographyE. Kuhl, P. Steinmann,
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BibliographyO. Manzoli, J. Oliver,
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BibliographyK. Park, G. Paulino, an
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BibliographyI. Singh, B. Mishra, an
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BibliographyG. Wells and L. Sluys.
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