Seismic response evaluation of historical masonry structures with nonlinear static and dynamic analyses

During the last decades the safeguard of historical masonry structures against seismic events has become an urgent problem for the engineers all over the world, especially for countries like Italy where the preservation of unique art and architecture masterpieces is of strategic importance. It has been proven that the masonry buildings are extremely vulnerable to ground motions, not only because of the design concepts that focused on the ability of the structure to support only gravity loads, but also due to the intrinsic characteristics of this kind of buildings. The current thesis is performed with reference to two types of historical masonry structures – towers (bell-towers, clock-towers, battle towers) and churches, all of them located in Veneto or Lombardy region. Numerical finite elements models are created and the study of the buildings starts with a preliminary modal analysis. The so-called N2 method, which synthetizes together non-linear static (pushover) analysis of a multi-degree of freedom system and response analysis of an equivalent single-degree of freedom system, was developed to verify the buildings under seismic actions. It allows for a comparison between the capacity of the structure and the seismic demand. Non-linear dynamic analyses using accelerograms normalized to 0.1g and 0.2g are consequently performed, whose results verify the procedure described above and proved that the N2 method could give a good approximation of the global seismic response of the masonry structures under the condition that it is used carefully according to the specifics of each building. The collapse mechanism in terms of the most vulnerable macro element was determined. Finally a comparison of the damage observed during the post-event survey and the one obtained by the analyses is made to confirm that the discussed combination of methods reflect the real damage sustained by the buildings during the Emilia-Romagna earthquake in May 2012.