Resumen
The assessment of seismic performance of existing masonry structures is a key aspect for the risk mitigation strategies of existing buildings and preservation of historical heritage. The increasing availability of modelling approaches for the assessment of seismic response of masonry structures calls for the need of verifying their reliability and correct use. In fact, these procedures are very sensitive to modelling hypotheses, so that the results of the assessment could vary in a wide interval depending on the adopted software and on the user?s skill. Aiming at enhancing the classical software packages for the structural analysis of masonry buildings, especially in terms of easiness of use, simplicity of modelling and limited computational demand, the authors developed a reliable and sound push-over program, called E-PUSH, which allows a quick and nearly user-independent assessment of the seismic risk index. In the paper, available commercial codes for the seismic assessment of unreinforced masonry buildings are illustrated and discussed, in comparison with the E-PUSH program, highlighting the differences in terms of modelling assumptions, choice of masonry mechanical parameters and failure criteria, focusing on the impact of the assumptions adopted for the estimation of capacity curves and seismic risk index of a simple benchmark structure. Then, a relevant case study, consisting in the assessment of the ?Niccolò Machiavelli? masonry school in Florence, is investigated adopting two different software packages, the original E-PUSH and a commercial one, discussing the sensitivity of the results on the assumptions made by the user in the modelling phase.