Discrete and continuum mechanical models to evaluate the behaviour to shear-compression loads and vibrations of masonry panels

The research presented focuses on limits and potentiality of discrete and continuum mechanical models to interpretate the structural performance and micromechanical properties of masonry panels [1] subjected to shear-compression loads and vibration effects. The dynamic parameters (frequencies and modal shapes) changing to incremental shear load were evaluated by Discrete Element (DE), Finite Element (FE), FE-DE models and compared to experimental results. DEM (Discrete Element Model) simulates the motion and interaction of masonry units assumed as rigid blocks interacting by elastoplastic interfaces. Brick failure mechanisms were considered by means vertical additional interfaces. FEM (Finite Element Model) represents masonry as a continuous system with diffused mechanical characteristics of material constituents by means homogenization procedure, [2]. FE-DE model is based on the interaction between elements which was handled by contact interfaces to simulate both the global behaviour and the damage evolution driven on experimental survey [3]. FEM can simulate performance capacities such as strength and deformability without identifying the crack pattern, with a reduced computational effort. On the other hand, procedures based on discrete elements (DE and FE-DE) require a burdensome and less manageable computational effort, which is however reduced in case of DEM for rigid block hypothesis, for the analysis of complex systems, but they allow for a reliable simulation of collapse mechanisms. The aim of this research is to assess the ability of the proposed numerical models to identify dynamic properties under varying boundary conditions and crack patterns, to define a predictive procedure that relates damage conditions to natural frequencies and mode shapes.