Assessment of in-plane shear behavior of historical andesite stone–Khorasan mortar masonry walls strengthened with CFRP-based techniques and repair mortar

Historic structures are highly vulnerable to horizontal forces from earthquakes due to their generally low tensile strength and rigid structures. Previous studies on these structures have revealed the need for retrofitting against earthquakes and led to the application of various methods. Carbon fiber reinforced polymer (CFRP) materials, with their superior strength-to-weight ratio, easy applicability and minimal intervention requirements, have recently emerged as an innovative technique preferred for the strengthening of historic masonry structures.

In the study, the repair and strengthening of method of an unreinforced stone masonry wall with different materials was applied and the in-plane shear behavior of the wall was investigated by experimental and numerical analysis. An unreinforced stone masonry wall (URM), called the “reference specimen”, was produced as the URM-R specimen. Repair mortar (URM-M) was used in the repair and strengthening of a stone masonry wall. A stone wall specimen was placed with CFRP bars (URM-B), two pieces in each joint of the wall, for a total of 8 bars. Two specimens were strengthened with CFRP bars, one with Khorasan mortar (URM-BK) and one with repair mortar (URM-BM).

CRFP laminate materials were also applied to two specimens either horizontally (URM-LH) or diagonally (URM-LD) on both surfaces of the URM wall. A comparison of experimental and numerical results showed that the URM-LD (CFRP laminate diagonal) specimen, the most effective of the methods tested, significantly increased maximum load, shear stress, ductility, and elastic stiffness. In addition, the URM-LD specimen reduced wall fragility and helped maintain wall integrity during fracture.