Out-of-plane performance of masonry infill walls strengthened with CFRP, polyurea spray, and aluminum stiffeners

In this study, the out-of-plane behavior of lateral hollow clay brick (LHCB) infill walls embedded within reinforced concrete beams was experimentally investigated. Within the scope of the study, specimens strengthened with CFRP strips, a polyurea-based sprayed coating, a hybrid CFRP + polyurea system, and vertical aluminum profiles were tested, in addition to reference walls with thin and thick plaster. The out-of-plane behavior of the specimens was compared in terms of maximum load-bearing capacity, initial stiffness, displacement capacity, energy dissipation performance, and failure modes. The experimental results showed that increasing the plaster thickness significantly improved the load-bearing capacity and energy dissipation performance. Although CFRP and CFRP + polyurea hybrid reinforcements increased the maximum load capacity by 110–140%, their energy dissipation capacity remained low due to brittle failure behavior. It was determined that the polyurea coating preserved the surface integrity of the brickwork but limited its ductile behavior. The highest performance was achieved in specimens reinforced with vertical aluminum profiles; this method increased out-of-plane strength by over 220% while increasing energy dissipation capacity by approximately 12 times. Additionally, it was found that the aluminum profiles prevented brittle spalling, enabling the walls to exhibit consistent behavior at high displacement levels. © 2026 Institution of Structural Engineers. Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.