| Traditional masonry walls have been designed as unreinforced or lightly reinforced to resist mainly the axial load. The risk associated with the seismic activity was therefore underestimated. Fiber reinforced polymer (FRP) composite materials can be used to strengthen these existing masonry elements, which are normally under-designed when evaluated according to modern codes for out-of-plane loading. Two series of reinforced masonry walls with externally bonded glass fiber reinforced polymer (GFPR) strips were tested in this study. The first series consisted of four 200 mm thick masonry walls and the second series consisted of four 150 mm masonry walls, both with externally bonded GFRP strips of various widths. Each specimen was 4 meters high and 1.2 meters wide. The primary objective was to study the behavior of reinforced masonry walls under out-of-plane lateral load. Response of the specimens under out-of-plane loading was extremely ductile and high mid-span deflection values were recorded. Three different modes of failure were observed: flexure-shear of masonry, delamination of FRP and tensile fracture of fibers. An analytical model to predict the out-of-plane behavior of reinforced masonry walls proposed by Kuzik et al. (1999) was modified to incorporate results obtained from the present study. Results obtained from the modified analytical model are in good agreement with the experimental results. A parametric study was conducted using the modified model to assist in the development of a design tool. Among the various parameters studied, amount of externally bonded GFRP strips has a clear and decisive effect in increasing the ultimate moment of the specimens. However, magnitude of constant axial load has insignificant effect. |
