New openings in unreinforced masonry walls under in-plane loads: a numerical and experimental study

Nowadays, existing masonry buildings are frequently modified to satisfy living demands. These modifications may require the addition of new windows or doors in walls of structural functionality. In engineering practice, such modifications are generally designed and verified for vertical loads while, for seismic loads, the changes in the walls' structural behaviour are not yet fully understood. Consequently, current design may incorrectly estimate the in-plane response of the perforated walls. This paper presents an evaluation of the effects of the introduction of new openings in masonry walls under in-plane loads by a numerical and experimental approach. Two parameters are considered for the numerical studies: opening size and eccentricity. The results show that the loss in stiffness and strength due to new openings are proportional to the opening area and that the eccentricity might change the wall response going from rocking to shear dominant behaviour, depending on the load direction.