Strengthened decoupled masonry infill walls: An experimental study on out-of-plane performance under cyclic loads

Decoupling masonry infill walls has emerged as an effective strategy to mitigate several structural issues associated with traditional interacting infills, including in-plane damage, which can lead to premature out-of-plane failure, and the potential for inducing structural irregularities and short-column effects. However, this decoupling also amplifies out-of-plane bending moments in the infills, rendering them more vulnerable. Various strengthening techniques were investigated in this study to enhance their out-of-plane resistance. 13 pairs of specimens of horizontally perforated clay block infill walls were subjected to cyclic out-of-plane loading to assess strength, displacement, ductility, energy dissipation, and stiffness degradation. The effects of different strengthening techniques, including plastering, improvement of bed joint mortar adhesion, polypropylene (PP) fiber-reinforced plaster, glass fiber reinforced polymer (GFRP) mesh in widespread and strip configurations, welded wire mesh, and galvanized steel chicken wire mesh, were studied. Results indicate that unplastered walls exhibit inadequate out-of-plane resistance, necessitating strengthening measures. Cement-sand plaster significantly improves wall strength, suitable for regions with moderate seismic and wind loads. Welded wire mesh and widespread GFRP mesh emerged as effective strengthening options for high and extreme seismic and wind conditions, while strip GFRP mesh requires cautious application. Although the application of chicken wire mesh can enhance flexural strength, its inherent brittleness, as evidenced by its low ductility and energy dissipation capacity, renders it unsuitable for regions susceptible to moderate to high seismic activity. The use of adhesive masonry mortar, while improving bond strength, suffers from similar limitations. These findings offer valuable insights for the design and retrofitting of decoupled masonry infill walls.