Comparative Study on the Seismic Performance of Retrofitted Multi-Story Masonry Structures in High-Seismic-Intensity Regions

To investigate the effectiveness of different strengthening techniques in improving the seismic performance of masonry structures in high-seismic-intensity regions， this study took a masonry structure in Tianjin as a case study. The dynamic responses and seismic performance of the structure were examined under seismic intensities of VII （0.1g）， VIII （0.2g）， and IX （0.4g） by applying ground motion inputs including the Tianjin wave， the El Centro wave， and artificial waves. Performance differences among the original structure， the bed-joint reinforced structure， and the seismically isolated structure were compared in terms of damage distribution， inter-story drift ratio， and floor acceleration. The results indicated that the bed-joint reinforcement technique effectively restrained the propagation of diagonal cracks at the corners of wall openings and controlled local damage through the restraint provided by rebars， while its effect on controlling inter-story drift ratios and roof acceleration was limited. The seismic isolation bearings significantly suppressed global structural damage， allowing the upper masonry to remain essentially elastic even under high-intensity excitation. Compared with the non-isolated structure， the inter-story drift ratios of the isolated structure were reduced by 51.91%-96.28% （X-direction） and 39.99%-87.11% （Y-direction）， satisfying the “intact” performance level under all scenarios， while the reduction in peak roof acceleration reached 55.81%-88.79% （X-direction） and 47.20%-88.64% （Y-direction）.