STRUCTURAL ASSESSMENT OF SANTA MARIA MADDALENA CHURCH IN ISCHIA ISLAND (ITALY) BY EXPERIMENTAL MODAL ANALYSIS UNDER OPERATIONAL CONDITIONS

During the seismic event of 21st August 2017 in Ischia, many masonry churches were damaged. Within the inspected damaged churches, a very interesting case study is represented by Santa Maria Maddalena church, located on the hill of Casamicciola Terme, near to the epicentre. The church of Santa Maria Maddalena can be considered a ‘unicum’, since it was built in 1896, after the catastrophic earthquake of 1883, with a ‘mixed’ structure made mainly of yellow tuff blocks walls strengthened by iron profiles or wooden elements. Several examples of structures made of masonry walls with wooden elements embedded in the wall thickness, i.e. the so called ‘baraccato system’ are present in the island, while the use of iron profiles is rare. The paper is firstly aimed to present the results of detailed historical investigation, geometrical survey, damage status analysis and provisional safety assessment after the earthquake of 21st August 2017. These activities were carried out in collaboration with the Campania Regional Directorate for Cultural Heritage (MiBACT). Within such a collaboration, an in situ dynamic test was also performed under operational conditions. The set-up and the results of this test are here presented in order to point out the main features of the structural system in terms of relevant modal parameters, both at global and local level.