1.School of Civil Engineering, Nanjing Institute of Technology, Nanjing 211167, China;
2.School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang 330013, China;
3.Institute of Geotechnical Engineering, Nanjing Tech University, Nanjing 210009, China
Abstract：Based on the influence law of dynamic pore pressure ratio changing on the stiffness of saturated sandy soil foundation, this paper proposes a novel and efficient shaking table model test method for the base-isolated structures on the variable stiffness foundation by controlling the time-holding compression ratio and intensity of the input ground motion. Besides, the influence law of the foundation stiffness on the dynamic characteristics of the base-isolation structure is also analyzed by combining with previous completed shaking table model tests of soil-pile-isolated structures on different foundations. The results indicate that the first-order natural vibration frequency of the base-isolation structure on variable stiffness foundation reduces with the increase of the relative stiffness ratio of structure to soil foundation. However, the damping ratio of the interaction system rises obviously, especially the isolation efficiency of the isolation layer decreases dramatically. The relative stiffness ratio of structure to soil significantly affects the floor acceleration response and interstorey displacement response of isolated structures. Compared with the rigid foundation, the larger the relative stiffness ratio of structure to soil is under strong earthquake, the more remarkable the floor acceleration response and interstorey displacement response of isolated structures are. Based on a series of shaking table model test results, the prediction formulas for the period extension rate, damping ratio, SSI influence rate of inter-storey drift angle, and SSI influence rate of displacement of isolation layer of isolated structure model with the small height-width ratio based on the relative stiffness ratio of structure to soil are preliminarily given in this paper. The research results of this paper can contribute to promote the more extensive application of structural vibration isolation technology.
Key words: Variable stiffness foundation; Base-isolated structure; Shaking table test; Dynamic characteristics; Isolation efficiency
于旭1,赵畅2,庄海洋2，陈国兴3. 变刚度地基上基础隔震结构动力学特性变化规律试验研究[J]. 振动与冲击, 2023, 42(7): 54-64.
YU Xu1, ZHAO Chang2, ZHUANG Haiyang2, CHEN Guoxing3. Test study on dynamic characteristics of base-isolated structure on variable stiffness foundation. JOURNAL OF VIBRATION AND SHOCK, 2023, 42(7): 54-64.
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