Numerical procedure for the assessment of seismic vulnerability of masonry buildings

Most of existing masonry buildings are located in seismic areas and many of them were constructed without a seismic code. So it is important to assess the seismic capacity of these structures and, if necessary, making strengthening interventions. The huge number of buildings that have to be analyzed implies that it is not possible to assess all of these at once because it requires a strong financial commitment. In this paper is presented a simplified strategy that permits to assess the seismic capacity of buildings on the basis of few data, collected during rapid inspections on site, and through simplified analysis. In this way it is possible to obtain a rough classification of all buildings on the basis of their seismic capacity, so to allow the Government to destine the financial resources available firstly to the buildings with lower seismic capacity. The simplified structural analysis to evaluate the shear action on each pier adopts a linear elastic approach followed by a shear redistribution so to roughly consider the actual nonlinear response of the structure. The procedure is also able to analyze buildings with flexible floors; in this case the shear force on each pier is proportional to its influence area. The results obtained with the simplified structural analysis are in good agreement with those obtained with more sophisticated programs. An application of the procedure to study a stock of fifty school buildings evidenced the easiness to construct a prioritization ranking for the seismic rehabilitation interventions on existing masonry buildings.