Buildings that incorporate masonry structure in countries with high seismic values are restrained by the norms in terms of force, to be used as plain masonry taking into account their fragile behaviour under alternating actions. In order to improve the masonry behaviour under seismic actions, an association of plain masonry with reinforced concrete was made to reach confined masonry with columns and belts, reinforced core masonry, or reinforced void masonry, etc. Consequently the research began on the autoclaved cellular concrete (ACC) masonry behaviour in the case of buildings erected in seismic areas and was focused upon the analysis of autoclaved cellular concrete (ACC) masonry with vertical hollows confined with disperse reinforced concrete when applied in low rise masonry buildings and which are situated in low seismic areas. The research was also justified by the fact that gas formed concrete exhibits several benefits as compared to brick masonry, namely: better thermal insulation, less manual work, reduced weight and implicitly lower seismic loads. The association of autoclaved cellular concrete (ACC) with disperse reinforced concrete in the case of confined masonry leads also to the removal of formwork and of reinforcement cutting. In this context the research is mainly concerned with the behaviour of autoclaved cellular concrete (ACC) masonry confined with columns and belts of steel fibre disperse reinforced concrete, both from theoretical and experimental viewpoint.