Out-of-Plane Behavior of Masonry Infills of Different Types and Slenderness Ratios under Reversed Cyclic Loading

The paper presents an experimental study on the out-of-plane (OOP) behavior of masonry infills in reinforced concrete (RC) frames. Three different types of masonry infills were investigated: burnt clay bricks, fly ash bricks, and autoclaved aerated concrete (AAC) blocks. Five full-scale specimens, each with an aspect ratio of one but different slenderness ratios (half-brick thick and full-brick thick), were subjected to reversed cyclic loading applied through airbags positioned on both sides of the infill. Results showed that the burnt clay brick masonry infill exhibited the highest strength, stiffness, and energy dissipation, followed by fly ash brick and AAC block masonry infills. Full-brick thick specimens demonstrated 4 to 4.7 times the strength, 2.1 to 3.5 times the stiffness, and 2.7 to 4.6 times the energy dissipation capacity compared to their half-brick thick counterparts. At smaller OOP displacements, the energy dissipation was small (about 5%–6% in terms of equivalent viscous damping) but increased rapidly once the masonry units started spalling. The experimental results, in terms of peak strength, were close to the values predicted by recent analytical models, which are based on large data sets of experimental and numerical results. Drift values for various damage states were consistent with those reported in the literature, except for the collapse damage state.