Failure of rectangular masonry buttresses under concentrated loading

The stability of masonry vaulted structures relies upon the ability of buttresses to sustain the thrust exerted by arches and vaults. Nevertheless, the stability of buttresses has been the subject of limited studies to date. This paper extends a previous investigation on masonry buttresses under arch or vault loading, where the horizontal force leading to overturning failure accounting for fracturing of the buttress before collapse was computed. The previous analytical solution, obtained by treating masonry as a continuum with no tension resistance, is compared with predictions from discrete element analyses. The latter consider masonry as an assemblage of rigid blocks with no-tension frictional joints and are based on time-stepping integration of the equations of motion of the individual blocks. Results of laboratory tests on models are also presented and compared with the analytical predictions. Collapse criteria by sliding and material failure are established and the effect of buttress leaning is also accounted for.