Research on the seismic mechanism of masonry walls with door-window openings reinforced by polypropylene mesh-composite cement mortar surface layer

In order to study the seismic mechanism of masonry walls with intricate openings reinforced by polypropylene mesh-composite cement mortar, three sets of specimens with door-window openings and one set of specimens without openings were designed and manufactured. Cyclic loading tests were conducted to observe the failure phenomena during loading, which to compare and analyse the hysteretic behavior, load-bearing capacity, and stiffness degradation of each specimen. Finally, finite element numerical simulation was also performed, and the calculation results were compared with the experimental results. The results indicate that comparing the walls after single-sided surface reinforcement and double-sided surface reinforcement to unreinforced wall,the ultimate load-load-bearing capacity increases by 28.06% and 95.1%, the initial stiffness increases by 40.92% and 49.70%, and the ductility coefficient increases by 22.87% and 50.98%, respectively. During loading, the wall without openings experienced shear failure along the horizontal joint, while the wall with openings experienced shear-compression failure at the corner of the opening and between the walls of the door-window. Compared with the wall without openings, the seismic performance indicators of the wall with openings are reduced. After using the polypropylene mesh-composite cement mortar surface layer reinforcement, the development of the main cracks in the wall was inhibited, resulting in the wall experienced diagonal shear failure at the opening corner, and the initial stiffness, seismic load-load-bearing capacity, and deformation capacity were increased. The characteristic load errors of finite element analysis and experimental results for each specimen were all less than 15%. In the wall without reinforcement, the damage was most severe in the wall limbs on both sides of the opening. After reinforcement, the wall damage extended from the walls between the door-window to the corners of the opening, and the distribution of damage was consistent with the experimental failure zone.