Stochastic nonlinear finite element analysis for collapse investigation of a historic stone balcony

Forensic investigations based on stochastic finite element (SFE) simulations can be a rational tool to assess the structural performance of existing structures, particularly in the case of ancient constructions which are affected by high uncertainty levels. In this study, the collapse of a historic piperno stone balcony is investigated through a series of nonlinear SFE analyses. After that the geometrical model of the element was created according to on-site and laboratory surveys, an experimental programme was carried out to characterise some physical properties and the mechanical behaviour of piperno stone. The latter is a volcanic building stone that has been used for a long time in the monumental architecture of Naples and Campania region in Southern Italy, so it is currently preserved by cultural heritage offices. Experimental data were found to be in agreement with those available in the literature for similar piperno stones. A Monte Carlo technique was used to reproduce the spatial heterogeneity of stone properties throughout the structural element, according to statistics provided by experimental tests. Nonlinear finite element analysis with displacement control was run for each random realization of material properties and assumption of boundary conditions, allowing a huge number of load–displacement capacity curves to be derived. The mean collapse load of the balcony was found to be very close to the total load expected at the moment of collapse, hence providing a proof to the forensic investigation.