Stress-strain characteristics of brick masonry under cyclic biaxial compression

Tests on half-scale and plast brick masonry specimens subjected to cyclic b iaxial compression were conducted for five principal stress ratios. An inte raction curve for the principal stresses at failure was obtained experiment ally and expressed mathematically in terms of stress invariants. The failur e under biaxial compression was characterized by midthickness splitting of the bearing area. The failure was quantified by the critical orthogonal str ain that governed the failure, which in turn defines the critical stress-st rain envelope curves. The critical envelope curve and the corresponding com mon point and stability point curves were expressed in mathematical form by general exponential formulas. The stability point curves can be used to es tablish the permissible stress level under in-plane cyclic loading.