The Cell Method (CM) code with automatic remeshing for crack propagation analysis [Ferretti (2003)] is here used for modeling the pullout test. Particular emphasis is given to the analysis in the Mohr-Coulomb plane, since previous numerical models were not decisive in describing failure mechanism in pullout tests. The interpretations of experimental and analytical studies vary widely, and none of the existing explanations offer a complete description of the progressive failure of the concrete medium [Yener (1994)]. Nor do most existing interpretations appear to be totally compatible with the experimental evidence. Analysis of the failure mechanism for the pullout test requires a failure criterion accurately describing crack initiation in tension loading. The Mohr-Coulomb criterion of the first code [Ferretti (2003)] has therefore been abandoned in favor of a more realistic criterion for the tensile state of stress, the Leon criterion. The failure analysis has been performed for several ratios between the counter pressure diameter and the stem length (Fig. 1). Moreover, the complete crack path has been obtained for the geometry of the Lok-test. The evolving state of stress-strain for the Lok-test is also provided. The identification of the directions of principal stress completes the stress analysis. Modeling is performed both on the concrete specimen and on the steel insert, showing how the CM can easily handle domains with several materials.
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