Il Patrimonio architettonico delle culture del Maghreb a rischio di scomparsa per perdita di conoscenza ed aggressione ambientale. Valutazione delle vulnerabilità e del rischio sismico della medina di Fes in Marocco

The research project intends to develop a methodology for the conservation of the architectural heritage in the Maghreb countries, threatened by both natural (in particular seismic events) and anthropic attacks (loss of knowledge and uncritical affirmation of technological cultures incompatible with the previous ones). The field of application of the study was the Medina of Fes in Morocco, considered a representative example of the processes and dynamics in progress. The theme of preservation of cultural heritage is investigated following a multidisciplinary approach in which the purely technical aspects have been addressed by seeking comparison with socio-cultural aspects. In order to gain an in-depth knowledge of the systems and construction types characterizing the area under investigation, it was decided to study the living and construction culture in northern Morocco and specifically in the Fes region, paying attention, thanks to field investigations, on the main critical points of the buildings and on the techniques that can be associated with the “rule of the art”, including those devices that seem to play a role in contrasting the seismic action. In addition, for the same purpose, a survey campaign was carried out on traditional masonry as representative of recurrent types, trying to associate a structural assessment with it and verify its mechanical properties. In particular, the following were carried out: a) physical-mineralogical analyses on mortar and brick samples; b) mechanical characterization tests, i.e. compression tests, indirect traction tests and three-points-bending tests for on brick samples; c) an evaluation of the efficiency of the different wall types through the application of the Wall Quality Index (IQM) integrating it into the GNDT data form; d) tilt tests on wall models to assess the contribution to the resistance in the plane of the walls by the wooden “radications”, characteristic of the local construction technique. The results obtained allowed to support the subsequent analysis phase related to the evaluation of seismic vulnerability, a subject that has not yet been sufficiently studied in the Maghreb area. A methodology is then proposed for assessing the seismic vulnerability calibrated on the specific characteristics of historical settlements (essentially consisting of patio buildings in aggregate) that can be extended and replicated in other similar contexts. The proposed method is based on the II level GNDT Vulnerability Index and allowed the realization of vulnerability curves, fragility curves, damage scenarios for different seismic intensities and loss scenarios. The results of the vulnerability assessment are also presented through their spatial distribution in the form of maps created in the GIS environment. Finally, the proposed methodology for the assessment of seismic vulnerability was applied a second time to the case study imagining that it had performed a consolidation of the building through the implementation of interventions for coherent and mechanically compatible with the historicized building structural reinforcement.