Strengthening of Masonry Walls against Out-of-Plane Loads Using Fiber-Reinforced Polymer Reinforcement

Thirty masonry walls strengthened using three different fiber-reinforced polymer (FRP) systems, with three anchorage methods, were fabricated and tested under a concentrated load over a 100 mm square area or a patch load over a 500 mm square area. The test results indicated a significant increase in the out-of-plane wall strength over the unstrengthened wall. While failure occurred in the unstrengthened wall by bending, four different modes of failure, that is, punching shear through the bricks, debonding of FRP reinforcement from the masonry substrate, crushing of brick in compression, and tensile rupture of the FRP reinforcement, were observed in the strengthened walls, depending on the types and configurations of FRP and anchorage systems. With appropriate surface preparation and anchorage systems, premature failure due to FRP debonding is prevented. Based on the principles of strain compatibility and force equilibrium, simple analytical models are presented to predict the ultimate load-carrying capacity of the strengthened walls. The test results compared well with the analytical predictions.