Seismic responses of classical masonry columns and colonnades simulated with the combined finite-discrete element method

As a common type of discontinuous civil engineering structures, classical columns and colonnades are assemblages of masonry blocks and mortar and widely found in ancient historic heritages. Since mortar always degrades significantly over ages, the dry -joint assumption is widely accepted for the analysis of such type structures. Earthquakes are hazardous to them and may lead to severe damages, even collapse. Finite element method (FEM) and discrete element method (DEM) have been widely used to simulate the responses of classical masonry columns and colonnades subjected to ground motions. However, potential fragmentation of masonry columns and colonnades cannot be fully simulated by FEM, due to inherent limitations on continuity requirement, or by traditional DEM, since masonry fracturing is ignored generally. In this study, the combined finitediscrete element method (FDEM) is employed to investigate the seismic behaviour of columns and colonnades subjected to ground motions, enriching its application in structural engineering. With a present FDEM model, structures are discretised by discrete elements incorporated with finite element formulation, resulting in more accurate deformation and interaction. A cohesive zone model accounting for the rupture of masonry blocks is implemented in the FDEM. Numerical examples are presented and validated, and simulations on a multi -drum masonry colonnade of the Forum in Pompeii are conducted. Key factors on seismic behaviour of the colonnade, such as PGA, predominant period, masonry fracturing and strengthening are investigated, providing beneficial suggestions on maintenance and protection of such architectural heritages. It is demonstrated that the FDEM is a robust tool to predict the seismic responses of masonry columns and colonnades subjected to ground motions.