Effect of position and size of openings on the seismic performance of masonry structures

In recent earthquakes, many masonry structures have been shown to have poor seismic performance. In particular, small to medium sized domestic structures, formed from masonry panels with openings such as doors and windows, have performed badly. Therefore, a better understanding of the impact of the openings on masonry panel performance is needed. A specific challenge is that even small windows or door openings can reduce the stiffness and strength of the masonry panels significantly, and this usually results in poor performance or collapse of the masonry structure under seismic loading. For characterizing the impact of openings in masonry panels, a series of numerical models with possible opening sizes have been studied under simulated seismic loading. This paper describes a set of parametric masonry panel models built using the code “3DEC” which is based on the Discrete Element Method (DEM). Unlike Finite Element methods, DEM allows significant displacements between the blocks to develop and new contacts are automatically recognized as part of the analysis. This analysis method is therefore able to capture the appearance of cracks, crack propagation and the failure patterns of the masonry walls. The models were created using deformable blocks for each brick along with a Coulomb-slip joint model for the mortar joints. A series of quasi-static pushover analyses have been developed looking at the impact of changing the position and size of the opening. Overall, this paper describes how the masonry walls were modelled, the
calibration of the numerical models and the analytical results from the parametric studies. A good agreement between this numerical model and data from previous papers results was achieved, verifying the reliability and
robustness of this approach. The relationships between the size and position of the opening in the panel and seismic performance of panel are described and discussed.