MILAD M. ALSHEBANI AND S.N. SINHA Indian Institute of Technology, Delhi
Experimental investigation into the cyclic behaviour of half-scale brick masonry under biaxial compression – tension was conducted. A total of thirty-two square panels was tested. The response of the panels under loading-unloading cycles was examined for four principal stress ratios with the angle between applied tensile stress and bed joints restricted to 0 degrees. Tensile stress was, therefore, applied parallel to the bed joint while compressive stress was applied normal to the bed joint. Failure of the panels was governed by tensile strains in the direction of applied tensile stress. The failure mode was brittle and characterised by a zig-zag pattern The principal stress at failure showed no significant change for principal stress ratios of 1.0 and 2.0, but decreased considerably beyond a principal stress ratio of 2.0. A failure interaction envelope curve for cyclic biaxial compression-tension is proposed in terms of normalised compressive and tensile principal stresses. It represents the outer boundary of a family of interaction curves which can be obtained if masonry is subjected to repeated loading and unloading.