Out-of-Plane Bending of Masonry Walls With Near-Surface Mounted and Externally Bonded Reinforcement

This paper presents an experimental investigation into the flexural behaviour of masonry walls that have been reinforced using near-surface mounted (NSM) or externally bonded (EB) reinforcement, under out-of-plane loading. The study simulates retrofitting applications and also proposes the NSM technique for new wall construction, using pre-grooved blocks, in lieu of the conventional method of internal reinforcing and grouting. To accommodate the NSM reinforcement, the grooves in the masonry blocks were aligned with ducts used to anchor the NSM reinforcement in the concrete footing. Seven wall specimens were tested, including walls reinforced with conventional and stainless steel bars, glass fibre-reinforced polymer (GFRP), and carbon FRP (CFRP) reinforcement. The study demonstrated the feasibility and effectiveness of the NSM technique for new construction. Walls with NSM reinforcement showed a superior performance to those with EB reinforcement. It was shown that increasing the FRP reinforcement ratio may result in a change of failure mode, and as such, the increase in strength may not be proportional to the increase in reinforcement ratio. NSM steel reinforced walls showed a superior performance in terms of strength, stiffness and the ductility associated with the formation of a plastic hinge at the base.