Issue 30

A. Fernández-Canteli et al., Frattura ed Integrità Strutturale, 30 (2014) 383-393; DOI: 10.3221/IGF-ESIS.30.46 387 both concrete specimen and pulling bars during the notch opening process thus provoking reactions and bending of the pulling bars. In this case, the bar is assumed to be perfectly rigid, so that the prescribed displacement in the pulling axis direction suffices to define the loading process. The material is modeled according to the so called “concrete damaged plasticity” model [22]. The mesh, load and boundary conditions are shown in Fig. 5. In this case, the size of the mesh is 5 mm, with a refinement in the ligament length up to 1 mm. Figure 4 : Mesh and boundary conditions used for model 1. Figure 5 : Mesh and boundary conditions for model 2. 3D-Model 3 using ABAQUS with free elastic lineal bars This model, see Fig. 6, once more developed in ABAQUS code, represents loads and boundary conditions in a closer manner to the real modified compact tension test than the former two handled. A displacement in the longitudinal X- direction is prescribed at the end of the bars thus restricting the movement (displacement or rotation) in any other direction. Modeling as 3D geometry implies considering a larger amount of elements. Due to non-symmetry reasons related to crack forming, as already exposed, no consideration of double symmetry, i.e. of a specimen quarter, is considered that would allow a significant reduction of the computational time. Exemplary, the element size is taken as 5 mm with a refinement up to 1 mm size in the ligament area and up to 3 mm in the perimeter of the hole where the bars are inserted. Prescribed displacement ( x  ) Prescribed displacement () Linear support Quasi-brittle material