Experimental and numerical investigations on the shear behavior of existing masonry structures

The great damages experienced by existing masonry constructions during the recent seismic events have highlighted the need of a systematic vulnerability assessment of this building typologies. One of the crucial aspect is the evaluation of the mechanical properties of the materials, which can be achieved through the execution of experimental tests. On existing buildings, it is often unpracticable to perform tests or, when they are performed, their reduced number and local nature do not allow to obtain reliable estimation of the mechanical parameters. Therefore, it is fundamental to identify experimental procedures having the minimum impact on the construction, obtaining, simultaneously, representative results. The scope of this work is to investigate the shear behavior of masonry structural elements, both from the experimental and the numerical point of view. In the first part of the research, an experimental campaign was conducted, in which slightly-destructive and destructive tests were performed on eight masonry buildings, damaged by the 2012 Emilia earthquake. The main objective was to evaluate the most suitable techniques applicable to get reliable information on the material properties. The tests results are analysed and discussed, focusing on the strength parameters obtainable from each test type and on the construction of appropriate failure domains. In the second part of the research, the shear-sliding failure mechanism was studied in detail through numerical simulations of triplet tests and shove tests, using a simplified micro-modeling strategy. The scope was to investigate factors that could affect the shear-sliding behavior of masonry. The results of the numerical analyses allowed to gain a better interpretation and understanding of the outcomes of the shear tests considered. The numerical models were validated through comparisons with experimental results. The understanding gained from the numerical simulations allowed to propose improvements of the testing procedure and of the results interpretation.