## 1 Introduction
Among them, dynamic nonlinear analyses may provide the most reliable prediction of the structural seismic behavior; however, they are scarcely employed in practice because of the required computational efforts and the difficulties in acquiring data (such as seismic input or material parameters to be used); therefore, in this case, their adoption is limited to specialized practitioners. For this reason, simplified nonlinear static analysis has been developed in the late 70's [17] in order to overcome such difficulties and with the target to provide easy-to-use computational tools for common practitioners as well. Nonlinear static analysis allows to evaluate the base shear-top displacement capacity curve under an incremental horizontal load profile, providing an evaluation of the performance point obtained by the intersection of the capacity curve with the displacement seismic demand. Nowadays, in common practice, nonlinear static analyses are combined with simplified structural models comprised by macroelements. Among the available modelling strategies which can be properly adopted, the so-called Equivalent Frame Method (EFM) [18] is the most widely used for seismic assessment of large URM buildings [19], which is characterized by regular geometry is based on the adoption of macroelements to discretize walls as an assemblage of piers, spandrels and rigid nodes. The EFM is based on strongly simplified hypotheses and several limits in its applicability have been highlighted in [20; 21]. However, it can be reasonably used for the seismic assessment of existing URM buildings which exhibit at a large extent a box behavior and with a quite regular opening pattern. It is usually preferred in professional practice, where a small computational burden and a time- and cost-saving structural analysis by using few mechanical parameters is needed. In this paper, attention is focused on the evaluation of the seismic behavior of an historic building realized in ancient URM and located in Perugia which has suffered serious damage during the 2016 Centro Italia earthquake [22]. Linear and non-linear analyses have been performed to reconstruct the seismic response of the buildings and in order to introduce suitable hypotheses of different types of retrofitting interventions useful to lead the building to an adequate safety level under dynamic loads. In particular, starting from the results obtained from the post-earthquake survey, nonlinear static analysis (pushover) has been performed considering the equivalent frame method (EFM) [18] to evaluate the in-plane collapse mechanisms and in order to calculate accurately the value of the behavior factor (q) which characterizes the structure and is used to carry out the linear dynamic analysis to obtain the out-of-plane behavior of the masonry walls. To complete the evaluation of the seismic vulnerability of the building, the analysis of local collapse mechanisms has been performed considering the kinematic approach [23; 24]. Finally, different types of retrofitting interventions have been proposed to guarantee an adequate safety level of the construction. The paper is organized as follows: in Section 2, the current configuration of the case of study is completely described, mechanical properties of materials assessed by means of in situ tests are reported. In Section 3, numerical analyses of current and retrofitted configuration are provided: EFM and kinematic analyses of the local mechanisms are carried out on both configurations and a comparison of the results is reported, highlighting the obtained improvement in seismic behavior of the case of study. In Section 4, some final remarks are drawn.