Interdependence of mechanical parameters on probabilistic seismic performance of masonry towers

The assessment of seismic performance of historical masonry towers is complicated by the lack of experimental data on the material properties. The peculiarity of these structures and their historical value render difficult performing experimental tests, particularly destructive ones. For each mechanical parameter, only reasonable intervals can be defined, mostly on the base of expert judgement. In the absence of a correlation structure among them, they are usually treated as independent variables. However, the selection of material parameters in itself is non-unique. For example, considering compressive strength, elastic modulus, and strain at elastic limit, there is no obvious choice of which two should be considered as input parameters, leaving the third as a derived quantity. In the paper, the effects of different choices on the probabilistic seismic performance are investigated. A significant role of the parameter interdependence is highlighted. The most safety preserving choice of independent parameters, in the absence of a desirable correlation structure, is the one in which compressive strength, elastic modulus, and strain ductility factor are treated as independent variables while the strain