Out-of-plane dynamic analysis of masonry façades interacting with sidewalls: comparison of discrete macro-element and rigid-block modelling

The lack of efficient connections between vertical members and between horizontal diaphragms and vertical members is detrimental to the structural integrity of masonry buildings. In these cases, the simple rocking of a façade may occur during earthquakes. The rocking motion generates a bouncing effect against sidewalls that must be considered in the dynamics of the system. This contribution discusses the dynamic performance of a masonry façade selected as a case study using different modeling approaches - namely, Discrete Macro-Elements and Rigid-Block modelling. Different acceleration ground motions, that is sinusoidal accelerations with amplitude 400 cm/sec2 and frequencies of 2, 5, and 10 Hz, and 50% of the 2009 L'Aquila earthquake, are applied to the façade. The results show a very good agreement between the two models in all the cases investigated, with lower differences for the restrained façade and the largest differences observed in the case of the unrestrained wall subjected to high-frequency sinusoidal loading. These differences are due to the different ways of modelling contact-detachment stages and to the non-infinite vertical stiffness of the DMEM. This contribution paves the way for an advanced modelling approach capable of simulating interlocking effects between the rocking wall and sidewalls in dynamic analyses through horizontally distributed nonlinear springs.