Behaviour of partially grouted hollow concrete masonry subjected to concentrated loads

An experimental programme was performed to study the behaviour of hollow concrete masonry wallettes with bond beams and vertical columns of grout subjected to concentrated loads. Forty-three wallettes were tested, with concentrated loads being applied either concentrically or eccentrically, through various-sized loading plates above the grout columns or on the bond beams above the hollow blocks. When the concentrated load was applied above the grout columns, the face shells of the hollow block units attached to the grout columns split and the columns subsequently crushed. When the load was applied on the bond beams, wallettes failed similarly to hollow masonry walls without vertical columns of grout, with web splitting and vertical cracking in line with the load, followed by face-shell spalling and (or) mortar crushing. When the eccentricity was one third of the wall thickness, failure was dominated by local spalling beneath the loading plate. The testing programme and mechanisms of failure are described, together with strength variation with increasing eccentricity, and dispersion of the concentrated load through the bond beam. General implications for the design of hollow concrete masonry with bond beams and vertical columns of grout subjected to concentrated loads are discussed.Key words: hollow concrete masonry, bond beam, grout columns, concentrated load, concentric, eccentric.