Shaking table tests on masonry structures retrofitted with steel-polymer mortar after earthquake damage

Masonry structures are widely used as residential buildings due to their intrinsic advantages, such as easily available materials, convenient construction, and durable thermal insulation. Recent earthquakes have shown that the masonry structures were severely damaged due to a relatively brittle seismic resistance mechanism. Therefore, the performance improvement and reconstruction of masonry structures after earthquake damage have gained significant attention. The steel and polymer mortar combination retrofitting method suitable for masonry structures after earthquake damage has been proposed in this study. Shaking table tests were carried out to assess the seismic performance of a half-scale two-story reinforced masonry structure (RMS) and a corresponding retrofitted test structure (R-RMS) strengthened by steel and polymer mortar. The dynamic characteristics, acceleration response, story drift response, and resulting strain were compared and analyzed. The results showed that the proposed retrofitting method could effectively improve the bearing capacity and seismic performance of masonry structures after earthquake damage and limit the development of plastic damage. In addition, the lateral stiffness of the masonry structure after earthquake damage was significantly improved, and the natural frequencies of the R-RMS model in the X-and Y-directions were increased by 257.35 % and 177.78 %, respectively. The acceleration amplification factor (AAF) of the R-RMS model in the X- and Y-direction of the 2nd story was increased by 69.67 % and 62.21 %, respectively. The story drift of the R-RMS model in the X- and Ydirection of the 1st story was increased by 76.61 %, 87.30 %, respectively, while the story drift of the 1st story was much smaller than that of the 2nd story under the rare earthquake intensity. The final damage of the 1st story of the R-RMS model was significantly lighter than that of the RMS model and the 2nd story of the R-RMS model. This study provides reference results for applying the proposed steel-polymer mortar to strengthen conventional masonry structures.