Abstract:To explore the influence of aspect ratio on the seismic responses of base-isolated structures built on flexible foundations, four traditional seismic-resistant and base-isolated frame structure models with different aspect ratios were established using ABAQUS finite element software. For different site conditions, models of base-isolated structures on both flexible and rigid foundations were established for comparison, so as to analyze the influence of Soil-Structure Interaction (SSI) effect on the seismic response patterns and isolation efficiency in structures with different aspect ratios. The results showed that with the increase of the aspect ratio, peak floor accelerations in isolated structures first decreased and then increased with increasing floor levels. Meanwhile, the displacement of the isolation layer continuously decreased, and the isolation efficiency gradually decreased. However, the variation patterns of the isolation efficiency with increasing floor levels were inconsistent among structures with different aspect ratios. For structures with smaller aspect ratios, the isolation efficiency was optimal at the top floor. As the aspect ratios increased, the optimal isolation efficiency layer appeared in the upper middle floors. Furthermore, by using peak floor acceleration, isolation layer displacement, and isolation efficiency as research parameters, it was concluded that SSI effect showed significantly stronger influence on isolation layers and top floor of structures compared to other floors. The SSI effect increased the displacement response of isolation layer in isolated structures and reduced the isolation efficiency of the isolation system. This adverse influence intensified with increasing aspect ratios of isolated structures.. Therefore, when designing isolated structures, the combined influence of the aspect ratio of the superstructure and the SSI effect on structures should be comprehensively considered.
