Material Characterization of Multi-leaf Masonry Walls in Historical Buildings: Non-linear FEM Approach

Masonry structures represent a substantial portion of the historical architectural heritage and encompass some of the most important monuments of cultural heritage worldwide. In order to preserve these existing buildings and understand their structural behaviour, it is necessary to examine in detail the complex non-linear behaviour of the historic masonry, coupled with the assessment of the mechanical characteristics of the constituent materials. This paper examines and discusses the results of an experimental campaign conducted on the multi-leaf masonry walls of the iconic St. Peter’s Basilica in Vatican. The investigation includes in-situ Minor Destructive Tests (MDT) using the flat-jack technique to assess the stress-strain behaviour of the external brickwork masonry panel. Additionally, core drilling is utilized to test cylindrical samples, to evaluate the mechanical properties of the internal Roman concrete core—“Opus Caementicium”. The objective is to use experimental curves to fine-tune 3D finite element non-linear numerical simulations, to assess material properties and uncertainties related to determining parameters for suitable constitutive models, such as the Drucker-Prager model. The paper extensively describes both the experimental investigation and the numerical Non-Linear Finite Element Analyses (NLFEA). Through this work, the intricate interactions among the masonry various components are highlighted, contributing to a deeper understanding of the architectural and engineering aspects of this historic structure.