Seismic behaviors of stone masonry walls between windows after POM-UHPC-embedded mortar joint reinforcement

A large number of stone masonry buildings have been constructed in the southeastern oastal region of Fujian Province, China. However, most of these structures exhibit poor seismic performance, likely due to low mortar strength and the absence of effective seismic-resistant system. By analyzing the construction characteristics and seismic vulnerabilities of stone masonry walls between windows, this study proposed a novel retrofitting technique that utilizes POM fiber-reinforced ultra-high performance concrete (POM-UHPC) for mortar joint reinforcement. To investigate the seismic behavior of the retrofitted stone masonry walls between windows, pseudo-static tests were conducted on three wall specimens with an aspect ratio of 1.43 (i.e., one specimen with full-embedding mortar joint reinforcement, one specimen with discrete-point-embedding (localized) mortar joint reinforcement, and one unreinforced specimen for comparison). The results show that the cracking load, initial stiffness, and shear capacity of the specimens with both full- and discrete-point joint reinforcement are significantly increased, and varying degrees of enhancement in their deformation capacity and energy dissipation are observed. When the effective area of POM-UHPC replacing low-strength mortar is similar, the discrete-point-embedding reinforcement method provides a greater improvement in the shear capacity of the wall between windows compared to the full-joint embedding method, but its energy dissipation capacity is lower. In practical engineering in the study area, the discrete-point-embedding mortar joint reinforcement method is recommended as the preferred approach. The findings of this study provide new technical support for the seismic reinforcement of stone masonry buildings in Fujian Province.