Extensive experimental, analytical and numerical research on seismic behaviour of multistorey shear walls with openings has been presented in the dissertation. Cyclic shear test of the multistorey specimen to simulate seismic response of the 5-storey high unreinforced masonry building, commonly built in Slovenia and broader region before 1964, when the first earthquake regulations were adopted in Slovenia, has been performed. The results of experimental research, carried out within the framework of this project, confirmed some basic assumptions regarding the mechanism of seismic behaviour of a single wall pier as a structural member of an entire masonry shear wall. The analysis of results of extensive measurements of forces and deformations as well as optical measurements of displacements over the surface of the entire shear walls subjected to seismic loading, made possible a realistic simulation of boundary and loading conditions when testing single wall elements. In order to
verify actual efficiency of modern techniques for an aseismic strengthening of existing masonry buildings, which have not been fully confirmed in practice yet, the cyclic shear test of multistorey shear walls has been terminated while major, but still repairable damage developed in the walls. Then, the damaged model was strengthened with fiber reinforced cement mortar based coating and re-tested up to near collapse limit state. The results of the experiment proved that the strengthening of masonry buildings using such technologies is efficient, as significant improvement in seismic behaviour (increased initial stiffness, 50 % higher seismic resistance and improved deformability) has been achieved. Within the framework of the dissertation, a macro element for the modelling of the cyclic response of the masonry has been developed and validated. It is capable of taking into account bending and shear behaviour as well as their interaction. In the final section, the validation of an efficient practical model for the evaluation of seismic resistance of the reference and strengthened building model, based on the formation of storey mechanism and on the application of the referential tensile strength of masonry, is demonstrated.