ABSTRACT
Damage occurrence develops mechanism of energy absorption that extensively reduces the forces acting upon the structure. It is connected with material defects localized in area where the principal tensile stress (stress concentration) exceeds the tensile strength of masonry material. Micro-cracking in masonry takes place at low load levels and progresses following non homogenous path which combines the two mechanisms with growth and linking between micro-cracks. It causes the reduction of the effective resisting area, leads to an increase of damage until rupture and can be described by the damage variable d. Micro-cracking causes the decrease of elastic modulus and the increase of stress in the masonry material (“effective stress”), having to resist the external loading (Oñate et al. 1996) – Figure 1. When the damage variable d reaches the critical value the micro-cracks start linking and the rupture comes into being.
