Parametric seismic analysis of hybrid masonry-reinforced concrete buildings

Past earthquakes evidenced the high vulnerability of existing masonry buildings, mainly due to lack of ductility and, consequently, seismic energy dissipation capacity. Hence, the need of improving their seismic performance led to the adoption of different types of retrofit interventions. The insertion of internal reinforced concrete frames in existing masonry buildings was widely adopted in the last century, mainly due to architectural and functionality matters. Despite increasing the global ductility of the structural system in most of the cases, such intervention significantly modifies the response to lateral loads, alongside their distribution among the vertical elements. Hence, specific approaches should be adopted for the assessment of the seismic vulnerability of this type of hybrid masonry-reinforced concrete structures. This issue is not comprehensively addressed in modern seismic design codes, leading to the adoption of oversimplified methods for analysis and design. In this paper, the seismic response of an archetype three-storey hybrid masonry-reinforced concrete building is assessed, by performing Pushover analysis. Particularly, parametric analyses were performed to investigate the influence of the relative lateral strength and stiffness between masonry walls and reinforced concrete frame. Lastly, the effect of the seismic loads distribution among the elements on failure modes was examined depending on the relative masonry-to-frame strength and stiffness.