The behavior of masonry shear walls is fundamental in the design of masonry buildings
subjected to different actions, namely of seismic nature. The usage of unreinforced, confined
or reinforced masonry is currently subjected to a strong debate in Europe due to the new
codes. In particular, the part of Eurocode 8 (Design of structures for earthquake resistance)
related to masonry structures is only a limited compromise for the different countries. A large
testing program was started at University of Minho in order to clarify issues regarding
confined masonry and unfilled vertical joints. Confined masonry is assumed as a hybrid
material joining masonry with small section horizontal and vertical lightly reinforced concrete
elements. This project, partly sponsored by the light-weight concrete block industry, aims at
defining adequate structural solutions for regions of low to high seismicity in Portugal.
This paper discusses the results of the experimental program, consisting mainly of masonry
walls subjected to cyclic actions and constant pre-compression. Sixteen specimens are
considered, being the shear strength, ductility, energy dissipation and stiffness discussed.
The key aspects under discussion are: (a) the possibility of replacing the filling of the vertical
joints by interlocking and horizontal bed joint reinforcement, (b) the need for filling vertical
joints in confined masonry solutions