Issue 51

M. Guadagnuolo et alii, Frattura ed Integrità Strutturale, 51 (2020) 398-409; DOI: 10.3221/IGF-ESIS.51.29 399 to preserve these buildings is linked to the need to transfer the Italian heritage, and therefore its history, to posterity. Moreover, this issue is as important as extremely complicated, above all due to the presence of an excessive degradation and the low seismic capacity that characterizes these structures [7, 8]. Due to the recent code developments and the increasing attention given to the seismic safety of existing structures, especially after the last Italian earthquakes, the analysis of existing built heritage and the improvement of its seismic performance have become a fundamental issue [9, 10]. The current seismic prevention strategy is based on a unitary approach that primarily envisages a risk mitigation through the seismic classification of the territory and the retrofitting and strengthening of existing buildings; and any contrast between conservation, interventions, and structural safety must be avoided [11-13]. The Italian guidelines for the assessment and mitigation of seismic risk of cultural heritage (Directive 2011) [14] provide specific indications for the assessment and reduction of seismic risk of protected cultural heritage. It specifies a path of knowledge, assessment of safety level against seismic loads and planning of possible interventions, conceptually similar to those provided for unprotected buildings, but suitably adapted to the needs and peculiarities of cultural heritage [15]. The Italian building heritage is characterized by high complexity and heterogeneity, both from an architectural and structural point of view. A significant number of old stone and masonry buildings do not comply with any provisions of current codes and have low seismic capacity and in general sophisticated analyses are necessary to assess their vulnerability [16, 17]. For all these reasons, is therefore essential to have lean procedures that allow the evaluation of the seismic risk assessment of existing buildings to establish priorities in a long-term prevention policy. In addition, it is important to define a methodology to obtain comparable results to plan future activities of analysis, evaluation and risk management. Due to the size and the number of buildings involved, the currently available methodologies for assessing the seismic vulnerability of urban areas usually require the treatment of an enormous volume of data associated with inspection and investigation work. For this reason, the use of simplified procedures is becoming more popular [18]. The vulnerability index method uses the information gathered about the main building parameters (plan, height, structural and non- structural elements, type and quality of materials), and is one of several general methods for seismic risk analysis. In [19] an easily manageable procedure is presented, adaptable to different buildings, but at the same time able to determine the current state of the structures and their structural deficiencies. The current conditions obviously lead to analyses aimed at improving the seismic performance of as much heritage as possible, avoiding the types of strengthening selected in the past that were not always suitable with respect to both the static condition and characteristics of the buildings and the respect of economic thresholds [20]. In fact, many strengthening adopted in the past have proved ineffective to withstand intense seismic actions [21]. In the present paper, a seismic analysis is performed by applying a simplified method for evaluating the safety index, before and after retrofitting interventions. Specifically, an approximate procedure is presented to optimize the type and quantity of the necessary local interventions. The analyses are performed with reference to two types of buildings that are particularly recurrent and representative of the built heritage in the province of Caserta and located into areas with different seismic hazard. The aim of the paper is to provide a first step to reduce the seismic risk of the analysed buildings, through very simple analyses of site and existing buildings. C ASES STUDY he present study analyses two residential buildings, representative of the great majority of the existing buildings in the historic centers of the province of Caserta but located into two areas with different characteristics. The choice of these two buildings is representative of the great variation that exists in cities even belonging to the same province. Although they are both noble buildings, belonging to two different periods and to two distinct cities is also pointed out in the constructive differences starting from the types of material used and from the development of the construction. These buildings were built in the XV century and in a period between 1800 and the beginnings of 1900. They are mainly simple or massive stones masonry buildings and develop around a court or a central courtyard, generally built for at least two or three stories. The buildings are isolated or enclosed in urban agglomeration, and usually have timber or steel floors and no thrusting roof. “Palazzo Petrucci-Novelli” The building was realized around the XIV century and it is a typical example of the construction typology of the area (Fig. 1). It is located in the historic center of Carinola (province of Caserta), a town that presents a medium-low seismic hazard. T