M. Weber1, P. Hahn2 and A. Sharma3
1)  PhD Student at University of Stuttgart
Pfaffenwaldring 4, 70569 Stuttgart, Germany
2)  Student at University of Stuttgart
Pfaffenwaldring 4, 70569 Stuttgart, Germany
e-mail: Philipphahn@web.de
3)  Jun.-Prof. at University of Stuttgart
Pfaffenwaldring 4, 70569 Stuttgart, Germany

Keywords: numerical modelling, angle of bed joint, biaxial stress, masonry elements

Abstract. The present paper describes the numerical investigations performed on masonry elements with different angles of inclination of the bed joints under biaxial deformation states by using the nonlinear finite element program MASA. First, the numerical model was calibrated on uniaxial compression tests. A micro-modelling approach was used, in which three-dimensional volume (solid) elements represented the stones and the joints and the constitutive law was described using the microplane model with relaxed kinematic constraint. The bonding properties were considered directly in the material behavior of the mortar. To reduce the computational effort, the geometry of the whole specimen was modelled as a quarter of the real dimensions using symmetry in two directions. With this model, an extensive numerical parametric study was carried out. Thereby the influence of the angle of bed joints, α was changed from 0 to 75 degrees with the horizontal in the interval of 15 degrees. For each angle of bed joints, different displacement ω1 and ω3 were applied in the principal direction 1 and 3. The displacements ω1 and ω3 were chosen in a manner that a tension-tension, a tension-compression, a compression-tension and a compression-compression state results. For each of this case, the ratio ω1/ω3 was changed between specified ranges. As the results of the numerical study, the characteristic of the constitutive law, the elastic properties and the softening behaviour will be investigated. In addition to the model calibration, first results of the numerical study were shown in this paper. The investigation serves as a basis for the development of a consistent mechanical model to describe the load-deformation behavior of masonry structures.