Risk Analysis of Historic Urban Areas

The purpose of this study is to assess the seismic risk of an urban area in the city of Salerno, characterized by an homogeneous historical buildings, datable to the first half of the 20th century. The preservation of this architectural heritage is essential for its symbolic and cultural value, and for its historical testimony.

This territory is grown up since the early years of the 20th century on the base of town planning projects developed especially in the period between the two world wars.

The preliminary phase of the research focused on the study of building and planning processes that led to the conformation of the observable areas today and to the search of special construction techniques. Indeed, in this urban context, constructive reality changes with respect to the canons of tradition and is a mirror of the particular historical moment, characterized by the advent of reinforced concrete which will lead to a new structural design of buildings. The constructions belonging to the beginning of the 20th century represent the results of an architectural knowledge, known as “transition period”, in which traditional and modern skills coexist, the first related to the rule of art and the second characterized by a copious experimental activity related to the industrial revolution [4]. In this period, architects and construction firms put great attention to the innovative techniques and materials, to the fascinating possibility of their use and to their durability.

The modernizing spirit which spread the country in those years, especially in Salerno, substantially led to the development of new experimental technologies, rather than stylistic and architectural ones [12]. Indeed, for the realization of the individual construction elements: patents and new techniques were introduced that concerned the new structural material: reinforced concrete. The work, focused on a large-scale area ofstudy, wants to contribute to the development of a methodological process that allows expeditious analysis of static and seismic risk of buildings belonging to the urban centers. As known, the seismic risk assessment of an urbanized area is related to the estimation of three basic parameters: the hazard, vulnerability and exposure. The hazard represents the probability of resentments in the investigated territory of the seismic intensity set; this is a function of genetic seismic areas (areas of foliation) next to the site of interest. The vulnerability, however, describes the propensity to damage of the built and depends on the intrinsic seismic resistance characteristics of itself. In the case of historical urban fabric, as shown by the recent earthquakes that struck the country (L’Aquila, 2009 – Emilia Romagna, 2012), these skills may be particularly reduced, considering both the limited abilities of built, as it was realized (lack of knowledge and/or appropriate regulations), and the deterioration of the buildings during time (a lack of maintenance and/or improper modifications). The work views the seismic risk assessment of the historical buildings located in an urban area of the city of Salerno using, for comparison, three different vulnerability assessment methodologies. These methods are based on statistical data and use parameters referring to the information collected in the AeDES (Feasibility and Damage in Seismic Emergency) first level form [1]: this was born as a check list to guide engineers involved in post-earthquake inspection campaigns engaged to evaluate the feasibility of the buildings, and can be used as an instrument for collecting data and topological metrics aimed at evaluating the vulnerability of ordinary buildings.

Then, intersecting the vulnerability data with the site hazards ones, it was possible to define city damage scenarios that, with the integration of more detailed analysis and specific strategies of prevention, aim at safety and the preservation of historical buildings.

Highlighting of the experimental area within the historic center of the city of Salerno. The main construction methods of the buildings analyzed in the study are shown

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