Modeling of The Pullout Test Through the Cell Method

The Cell Method (CM) code with auto-matic remeshing for crack propagation analysis [6] is here used for modelling 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 ex-perimental and analytical studies vary widely, and none of the existing explana-tions offer a complete description of the progressive failure of the concrete medium [21]. 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 ac-curately describing crack initiation in ten-sion loading. The Mohr-Coulomb criterion of the first code [6] has therefore been abandoned in favour 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 counterpres-sure 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 analy-sis. Modelling is performed both on the concrete specimen and on the steel insert, showing how the CM can easily handle domains with several materials.