Response of confined masonry with crumb rubber–fly ash bricks under cyclic loading

The structural performance of confined masonry and conventional infilled frames made with modified fly ash–crumb rubber bricks as an infill material under cyclic loading was investigated. Six specimens were tested – two bare frames (BF1 and BF2), two conventional infilled frames (IF1 and IF2) and two confined masonry infilled frames (CIF1 and CIF2). BF1 was subjected to monotonic loading, while the remaining specimens were tested under cyclic loading. Their performance was evaluated in terms of yield load, ultimate load, initial stiffness, energy absorption, ductility ratio, displacement and deformation patterns. Compared with the IF specimens, the CIF specimens demonstrated superior performance with an average 27.6% higher initial stiffness and 17.4% greater peak load capacity. CIF1 recorded the highest ultimate load of 245 kN, 109% greater than that of BF2 and 19.5% higher than that of IF2. The energy absorption capacity of the CIFs was also the highest, indicating superior energy dissipation capacity. Failure of the BF specimens was dominated by plastic hinge formation, while the IF and CIF specimens showed combined shear and flexural cracking. Minimal separation at the masonry–frame interface in the CIFs affirmed the effectiveness of confinement and toothing.