Experimental investigation on cyclic in-plane behavior of URM walls retrofitted with AFRP

Abstract

URM buildings have been the most common constructions globally, although they are weak because of their low lateral strength against seismic loads. The seismic response of URM structures is highly dependent on the in-plane and out-of-plane behaviors of their load-carrying walls. As in-plane behavior, the shear failure has been known as the most brittle failure mode of URM walls. Although the monotonic response of the walls has been investigated widely, there is relatively less knowledge about their hysteretic response as well as the impact of seismic retrofitting on it. Considering the brittle nature of the in-plane behavior, the Aramid Fiber Reinforced Polymer (AFRP) sheet as a relatively soft member of FRP products was chosen as the retrofitting choice in this study. As an experimental study, cyclic lateral loading was applied to the bare and AFRP retrofitted masonry wall specimens in a displacement-controlled manner. To study the shear behavior of the AFRP retrofitted masonry wall specimens, the specimens were externally retrofitted with AFRP sheets in two different configurations; fully and diagonally wrapped. The load-deformation behavior of the walls during the cyclic loading was investigated using hysteresis diagrams. The test results revealed that AFRP retrofitting could improve the shear strength by about 75% and 81% for fully and diagonally wrapped specimens, respectively. Also, the integrity of URM walls was enhanced without altering their lateral stiffness. Moreover, the fully-wrapped specimen exhibited a deformation capability of about 37% higher than the diagonally-wrapped one. Furthermore, the failure of the fully-wrapped specimen was controlled by toe crushing of the masonry wall, while the rupture of the retrofitting sheet caused the failure in the diagonally-wrapped specimen.