Discrete-element analysis of floor influence on seismic response of masonry structures

Traditional masonry buildings are highly vulnerable to earthquake loading and their dynamic response is strongly influenced by the in-plane deformability of the timber floors and the quality of the wall-to-floor connections. Understanding the behaviour of timber floors and roofs and their interaction with masonry walls is therefore fundamental for the protection of historical buildings. In a previous research project, different timber-based dry-connected strengthening solutions for timber floors were tested under in-plane loading. The experimental results showed a significant increase in shear strength and stiffness. In the current study, the discrete-element method (DEM) was used to model a simple masonry structure and evaluate the effectiveness of strengthening solutions to avoid triggering first-mode mechanisms, namely out-of-plane collapse of masonry walls. The structure was stressed by seismic ground accelerations. The unreinforced and reinforced floors were modelled with non-linear springs that reproduced their experimental hysteretic response. Parametric analyses were performed, changing the geometry of the structure and the masonry wall thickness. The comparison highlighted the effectiveness of the proposed wood-based strengthening solutions for reducing out-of-plane displacements of masonry walls, potentially matching the performance of rigid floors.