Limit Analysis of Loaded Out-of-Plane Rubble Masonry : A Case Study in Portugal

An integrated methodology for the characterization of the response of rubble masonry is presented.The behaviour at collapse of a wall belonging to the Guimarães castle (Portugal) is investigated through a rigid-plastic homogenization procedure, accounting both for the actual disposition of the blocks constituting the walls and texture irregularity, given by the variability of block dimensions.A detailed survey is conducted by means of a photogrammetric technique, allowing for a precise characterization of blocks dimensions and disposition.After a geometric simplification assuming mortar joints reduced to interfaces, homogenized masonry in-and out-of-plane strength domains are evaluated on a number of different representing elements of volume (RVEs) having different sizes and sampled on the walls of the castle.Strength domains are obtained using a finite element (FE) limit analysis with a heterogeneous discretization by triangles and interfaces.Finally, a series of limit analyses are carried out on the façade for the safety assessment under seismic loads by means of two numerical models, the first one being a heterogeneous model and the second a homogenized approach.The reliability of the results, in terms of limit load and failure mechanism, provided by the homogenized model, when compared to the heterogeneous one is satisfactory.