Strengthening of Masonry Structures Using Epoxy-Bonded FRP Laminates

The present study presents a systematic analysis for the short-term strength of masonry walls, strengthened with externally bonded fiber reinforced polymer (FRP) laminates under monotonic out-of-plane bending, in-plane bending, and in-plane shear, all combined with axial load, within the framework of modern design codes (e.g., Eurocode 6). The results, which are presented in the form of both design equations and normalized interaction diagrams, show that: (1) when out-of-plane bending response dominates, as in the case of upper story levels, where axial loads are low, the increase in bending capacity is quite high; (2) in the (rather rare) case of in-plane bending, high area fractions of reinforcement placed near the highly stressed zones give considerable strength increases (regardless of the axial load), provided that premature peeling-off of the laminates is prevented; and (3) the in-plane shear capacity of FRP-strengthened walls can be quite high, too, especially in the case of low axial loads. The results obtained from monotonic four-point bending tests on wallettes confirm the analysis of both out-of plane and in-plane response and emphasize the important role of failure through FRP shearing beneath the bond.