Multilevel approach to the vulnerability analysis of historic masonry buildings

Research focus

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The aim of the research is to achieve deep knowledge on the structural behaviour of historic masonry buildings for the prevention and/or repair of damages caused by earthquakes. The collected data concerned concerning in detail: i) the technological and constructive characteristics of the surveyed buildings; ii) the material and structure properties (with particular reference to the constructive techniques and to the materials used for load-bearing masonry); iii) the materials and the techniques used for restoration before the earthquake; iv) the collapse mechanisms of the buildings and structures due to the earthquake, considering also the ones already retrofitted. The objectives of the research were: (i) to define a methodology for the vulnerability analysis of historic buildings at the level of the historic centre, (ii) to collect information on the effectiveness of the repair techniques both traditional and new, (iii) to set up Databases storing the information useful to prepare rescue plans, (iv) to use the collected knowledge for the implementation of reliable models for the vulnerability analysis, (v) to prepare guidelines for investigation and vulnerability analysis; (vi) to suggest a “minimal” investigation program, which can support the designers in their projects. The research was carried out, financed before by the Italian Civil Protection Department together with GNDT/INGV, on pilot sites in Umbria partially damaged by the 1997 earthquake and in Liguria, and by the Italian Civil protection Department under the RELUIS Project. The careful damage evaluation, based on the knowledge of the constructive techniques, of the materials and of the past interventions was particularly useful for the comprehension of the collapse mechanisms and to prevent future damages. These methodologies are particularly effective for the investigation and evaluation of the damage and for the choice of the most adequate friendly techniques for repair. This is in order to avoid the use of invasive and incompatible techniques. The research aim was also to suggest a "minimal" investigation program, which can support the designers in their projects. The knowledge of existing buildings is approached by considering different analysis levels: history, materials, structural morphology of the wall section, observed damage mechanisms, effectiveness of retrofitting techniques. The methodology was applied to four historic centres all located in Umbria (Italy). The survey of the buildings allowed to define an abacus of the typical collapse mechanisms, useful to define the seismic vulnerability also for other similar centres and to critically evaluate the past and future repair techniques. An improvement was made in the application of flat jack to characterise the different masonry typologies from the mechanical point of view in order to measure parameters as Young modulus and Poisson ratio, useful for the structural analysis. Following the collection and interpretation of data on the four centres an abacus of collapse mechanisms has been implemented which can be used to understand types of failures after an earthquake or to choose friendly techniques for repair of historic buildings. The data will be subdivided into: (i) isolated buildings, (ii) rows of buildings, (iii) complex buildings and into (i) non repaired buildings (ii) repaired buildings. A survey and critical revision of the strengthening and repair interventions before 1997 was made. Within the descriptive templates (survey form) of each surveyed building a section exists describing the intervention projects presented after the 1979 earthquake as they were given to the authors by the Municipality offices or as surveyed directly on site. The damage investigation also allowed to collect data on the traditional techniques applied before the 1979. It was so possible to carry out a 179 critical review of all the applied techniques and to define the most appropriate for the studied cases. The collected data were statistically elaborated.

Dipartimento di afferenza

Dipartimento di Ingegneria Strutturale (DIS)

Docenti afferenti

Full Professors
Luigia Binda
Chiara Molina
Associate Professors
Anna Anzani
Elsa Garavaglia
Assistant Professors
Antonella Saisi
Giuliana Cardani
Cristina Tedeschi