Parameter optimization of isolator in structure with added floors and related shaking table tests

The optimal parameter of lead laminated rubber bearings (LRBs) has been studied in the old masonry structure strengthened with external frames and added floors by using the middle story isolation technology. Elastoplastic analysis and shaking table tests are performed after the parameter for LRBs is optimized. The ratio of shear to weight in the isolation layer is selected as the control parameter of the isolator, and several models are established in order to analyze the base shear force of the structure and the displacement of the isolation floor with different isolator parameters. The results show that the response of the structure greatly reduces when the parameters of the isolation floor are selected in a certain range. The isolating effect is still good even after the structure is in the plastic stage. The shaking table tests show that the TMD effect of the superstructure is better with the increase of the earthquake input amplitude. The isolating effect still exists after the structure is damaged under the large earthquake, but it's not as good as the undamaged structure, which is in line with the theory.