Avaliação do comportamento anisotrópico do material com método dos elementos discretos formado por barras

Abstract

The literature shows that the compressive strength of the concrete can vary according to the direction of application, presenting a different behavior when requested in the parallel direction or in the direction normal to the concrete launch. Another factor influencing the compression response of the concrete is the confinement or the restrictions in the boundary conditions, which are observed experimentally in the friction at the interface sample-plate of the press, being that compressive strength of the concrete increases with the addition of same. This work presents a numerical study on the anisotropy in the concrete, created by the interfaces between the aggregate and the matrix and the change of its behavior with the boundary conditions. For this, it is proposed a way to simulate this type of anisotropy through the Lattice Discrete Element Method (LDEM). In this version of the LDEM the continuum is represented by a space bar lattice with the mass concentrated at its ends, in which bars in one direction have their tensile strength decreased, thus generating a certain degree of anisotropy of the simulated sample. Cubic test specimens were submitted to compression by the contact of steel plates made with the finite element method (MEF), under two boundary conditions, set and frictionless. This mixed model was implemented in comercial software Abaqus /Explicit. Three variations of the randomness of the material in the LDEM were analyzed, allowing to verify their influence on the obtained response. The results showed the influence of the boundary condition on the response of the material as a function of the direction of the request and a lower variation of the resistance between the directions of request for the test in the set condition was found. The request in the direction considered parallel to the casting of the concrete was the one that presented greater resistance compared to the request in the normal direction. With the increase of randomness of the material it was verified that the variation of the resistance as a function of the direction of loading tends to decrease. It was also possible to observe the difference in the shape of the rupture, for the test embedded the rupture occurred in a bi-conical format and in the case without friction the cracks propagate parallel to the launching presenting a columnar shape.