Shear strength behavior of infill walls strengthened by carbon fiber reinforced cementitious matrix

Masonry infill walls have important effects on dynamic characteristics of buildings, which have a reinforced concrete frame structural system. Despite those important effects, masonry infill walls are usually neglected as structural elements in building analysis. Under lateral loads that are developed in moderate seismic regions, infill walls dramatically increase the stiffness of RC frames by acting as diagonal struts. Also, composite nature of the frame-infill wall system changes the magnitude and the strain distribution within the frame members. This paper presents a retrofitting methodology of infill walls using fiber reinforced cementitious matrix (FRCM) as a lateral load resisting element. FRCM is a structural composite material consisting of a carbon mesh, which acts as continuous reinforcement and a stabilized inorganic matrix, which joins the mesh to the infill walls. Inorganic matrix is comprised of a pozzolanic hydraulic binder that is highly compatible with the masonry support from chemical, physical, and mechanical aspects. In order to determine the effects of FRCM on the behavior of infill walls, an experimental study was conducted. Diagonal tension tests for nine infill wall specimens (755 mm × 755 mm) were conducted in order to observe the effects of different FRCM types over initial stiffness and shear strength. Test results showed that FRCM composites considerably increased the shear strength and stiffness of the infill walls and prevented the undesirable failure modes.