Engineered masonry infill walls joints for post earthquake structural damage control

The paper presents some of the results of an experimental campaign on the behaviour of engineered masonry infill walls subjected to both in and out of plane loading. Tests on large-scale specimens and masonry subassemblies were performed in order to evaluate the infill deformation capacity, the damage associated to different drift levels and the mechanical properties of the infill components. A design solution with sliding joints for both reducing the infill-frame interaction and ensure out of plane stability, already proposed in a previous study, was developed and refined with focus on construction details. The aim of the sliding joints is to ensure a predetermined mechanism in the infill wall, governed by hierarchy of strength, capable of ensuring ductility and energy dissipation to be taken into account into the design practice, thanks to the predictability of the infill response. In the test described in this paper the infill wall specimen reached up to 3% in-plane drift with very little damage and supported an out of plane force equivalent to a horizontal acceleration 4 times the acceleration of gravity. The force-displacement hysteretic curve and crack pattern show the efficiency of the construction technique, based on affordable and tradition-like construction process and materials, in ensuring very deformable, ductile and stable response to the masonry infill.