## 1 Introduction  
The seismic resistance of critical infrastructure buildings is a key feature of community resilience, as earthquakes have caused more than 745,000 casualties and reported losses amounting to 661 billion USD worldwide over the past 20 years (1998-2017) [1]. Hospitals and other important health facilities are counted as critical infrastructure and it is of the utmost importance that they remain fully operational after an earthquake. The seismic vulnerability of health facilities at a large scale has been studied by various authors (e.g., [2, 3, 4, 5, 6, 7, 8]). However, detailed seismic performance assessmentsof individual buildings, which should be made for all buildings of strategic importance, have been reported very scarcely. For example, in [9], the authors assessed the seismic vulnerability of an existing eight-story reinforced concrete (RC) hospital building, using numerical analysis and field monitoring data. The proposed methodology included the derivation of \"time-building specific\" fragility curves for a building. They concluded that field monitoring data is a very useful tool for determining the actual state of a building, which may differ significantly from the state assumed from the available design and construction documentation plans, and therefore, the structure may be more vulnerable than expected. A further interesting approach to perform the seismic assessment of individual buildings, that may also be used for health care facilities, using several independent computer objects, has been presented in [10]. [PERSON] [11] evaluated the seismic vulnerability of the irregular RC hospital building of Avezzano in Italy using the pushover method, and studied the sensitivity of torsional inelastic responses to lateral force distributions, higher mode contributions, accidental eccentricity and controlled points for monitoring the target displacement. [PERSON] et al. [12] studied the seismic performance of a real RC asymmetric hospital building, using different approaches to model (linear and nonlinear) and different analysis methods in accordance with the Italian technical code \"Norme tecniche per le costruzioni\" NTC 2008. They concluded that the applied analyses showed important differences in local and global seismic responses, and that the final results of the building safety level might be very different. However, they suggested the adoption of nonlinear procedures, but with caution and by expert engineers, because of the complex nonlinear behavior of structures that had to be tackled. It is necessary to point out the lack of studies presenting a seismic assessment of irregular buildings consisting of lightly reinforced concrete walls. These structural systems are common in buildings in seismic areas and their performance has proved to be satisfactory in the case of very strong earthquakes [13], but if the ductile mechanisms are not provided, highly inelastic and dangerous complex mechanisms may occur [14]. Accordingly, considerable attention needs to be paid to creating element failure models. A contribution to the seismic performance and loss assessment of old RC wall-frame buildings has been made by the authors of [15]. In this study, a loss estimation methodology for old RC frame-wall buildings characterized by non-ductile columns and RC walls made with smooth rebars and light transversal reinforcements has been proposed. These structures were analyzed in detail and their seismic vulnerability was assessed. The fragility functions of non-ductile RC walls with smooth bars were developed for the purpose. An interesting case-study of an irregular high building with RC walls has been provided by [16] in which the authors identified the possible reasons of building collapse during the 2010 Chile earthquake. The damage of code-conforming reinforced concrete buildings during that earthquake also motivated the research presented in [17] in which a Chilean code-conforming reinforced concrete office building was designed, consisting of shear walls and moment frames.