GNGTS 2013 - Atti del 32° Convegno Nazionale

Hence, the error introduced by the use of less detailed (but easier, faster and less expensive to collect) data is analyzed and discussed in order to evaluate the reliability of alternative data sources within a cost/benefit approach to large scale seismic risk assessment. Avellino city. The case study here described has been conducted in the area of the Municipality of Avellino, in the Campania region (Southern Italy). Avellino was struck strongly by the disastrous Irpinia earthquake of 23 November 1980. Measuring 6.89 on the Richter Scale, the quake killed 2914 people, injured more than 80000 and left 280000 homeless. Towns in the province of Avellino were hardest hit and the Italian Government spent during the last thirty years around 30 billion of Euro on reconstruction. Consequently to the earthquake and to regulate the reconstruction activities, several specific acts, decrees, zoning laws and ordinance have been issued: the first one was the Law n. 219/1981 (Legge n. 219 del 14/5/1981), that entrusted the urban planning to the damaged Municipalities, under the coordination of the Campania Region. In the same year, Avellino was also classified for the first time as seismic in technical building code (Decreto Ministeriale del 7/3/1981). Seismic hazard. In the present study, seismic hazard is evaluated according to the Italian National Technical Standards (Decreto Ministeriale del 14/1/2008). According to these standards, the seismic hazard is defined in terms of the maximum horizontal expected acceleration in free field conditions on a rigid site of reference with horizontal topographic surface, and in terms of the elastic acceleration response spectrum, with reference to pre- defined exceeding probability over the reference period. The spectral shapes are defined according to the exceeding probability during the reference period (P VR ), from the following parameters values referred to rigid horizontal site: • a g maximum acceleration at the site; • F 0 maximum value of amplification factor of the spectrum in horizontal acceleration; • T C * value of the initial period corresponding to the constant speed branch of the spectrum. These parameters, which are tabulated in Annex B of NTC, are provided by (INGV-DPC S1, 2007) in correspondence to the points of a grid whose nodes are sufficiently close together (not more than 10 km away), and for different return periods T R , that fall into a target range between 30 and 2475 years, extremes included. Stratigraphic effects are taken into account depending on the soil category of the site of interest, provided by a microzonation study. Field survey data. Building stock data have been collected through a detailed field survey carried out by means of a survey form implemented in a tablet PC. In particular the survey was developed through specialized operators who compiled a survey form subdivided in different sections, with an increasing level of detail. The survey form includes the main parameters – among the ones that can be reasonably collected during a field survey – that may have a significant influence on building seismic capacity, addressing a particular attention to specific potential sources of seismic vulnerability, among which the most important are the structural typology, the age of construction (defining the codes and the rules used to build them), and the number of storeys (affecting the dynamic properties of buildings). Moreover, detailed geometric and morphologic data were collected, such as plan shape, interstorey height, bay Fig. 1 – a) Structural typology; b) number of storeys of RC buildings; c) age of construction of surveyed buildings. a) b) c) 51 GNGTS 2013 S essione 2.1