Experimental investigation on the torsion-shear interaction between stone blocks in frictional contact

The definition of the yield domains within limit analysis of 3D dry-jointed masonry block structures requires experimental and analytical investigation on the frictional contact problems. In this paper the torsion-shear interaction is experimentally investigated with reference to the single contact interface of a stack of two dry-jointed tuff blocks. A number of tests based on different eccentricities and directions of the horizontal loading are carried out in order to consider interactions between shear and torsion moment. The results are compared with those obtained by the analytical model of two overlapped rigid blocks, based on the assumptions of infinite compressive strength for blocks and no-tension and frictional behaviour at their contact. In particular, the non-linear yield function in torsion-shear interaction is piecewise linearized in order to provide a simplified and conservative expression for inclusion in linear programming (LP) formulations.