Intervention on diffused architectural heritage in seismic area: which investigations for which intervention?

The structural diagnosis is a key point in the preservation strategies of the historic buildings; it is often aimed at addressing the possible options - cultural and technical - for the preservation and/or repair, assessing the structural and materials conditions, as well as the possibilities and potential vulnerabilities of the building. The processing of the collected information leads to the formulation of projects and use strategies that have, as main priority, the safety of the structure with full compatibility with the building characteristics. The analysis involves research aimed at a) recognizing - and evaluating - the technological and morphological characteristics - or any pathology - through visual inspections, b) collecting data concerning the building evolution, c) surveying the geometry, the cracks and the structural discontinuities, d) the mapping of the surface decay, e) characterizing sampled materials through laboratory tests, f) studying detected problems through on-site tests. Despite the requests of the Italian Code, the knowledge process is often overlooked or carried out only superficially, being often considered a waste of resources. The paper analyses the main problems affecting the architectonic heritage and the suggested diagnostic solutions; the possible risks of un-reliable structural assessments and interventions are underlined.