Experimental investigation of infill walls strengthened with fiber-reinforced composites

Infill walls are often excluded from structural design; however, they play a decisive role in the seismic performance of buildings. In this study, four full-scale brick masonry infill wall specimens constructed within a single-bay steel frame were tested under cyclic lateral loading. Among the specimens, one was bare brick (REF-2), another was a conventionally plastered wall with cement-based mortar (REF), while the remaining two were strengthened using Fabric-Reinforced Cementitious Matrix (FRCM) and finished with different plaster types: lime-based plaster (FRCM-2) and cement-based repair mortar (CBSM-FRCM). The experimental results demonstrated that both plaster type and FRCM strengthening significantly affect structural behavior. The CBSM-FRCM specimen exhibited the highest lateral load-bearing capacity, stiffness, and energy dissipation, with substantially enhanced performance in both push and pull directions compared to the reference specimens. In contrast, the FRCM-2 specimen achieved the highest ductility, highlighting its superior deformation capacity. The conventionally plastered REF specimen provided noticeable improvement over the bare REF-2 wall but remained inferior to the strengthened systems in terms of capacity and deformation. Overall, cement-based plasters provided superior adhesion and compressive strength, thereby enhancing load transfer and energy dissipation, whereas lime-based plaster improved ductility and deformation capacity. These findings underline the critical influence of plaster type and FRCM application in improving the seismic performance of masonry infill walls.