Shaking table test of pile-soil inter-story isolated structure under far-field long-period ground motion

Considering soil-structure interaction (SSI) effect on soft soil foundation will affect the seismic isolation effect and dynamic characteristics of the isolated structures. The seismic response of long-period structures such as isolated buildings under the far-field long-period ground motion is strong, which may be greater after considering the SSI effect. In order to explore the mechanism of dynamic response and seismic isolation performance of the system of pile, soil and inter-story isolated structure under the far-field long-period ground motion, the shaking table test was carreid out on the model of the inter-story isolated structure on the soft soil foundation. The story acceleration and displacement response of the isolation layer and the isolated structure under the far-field long-period ground motion and ordinary ground motion were compared and analyzed. The results show that the soft soil foundation has an obvious filtering effect, which can mitigate the high-frequency component and enlarge the medium and low-frequency components. The seismic isolation effect of the inter-story isolated structure under the ordinary ground motion is more significant, and the seismic isolation effect decreases with the increase of the peak ground acceleration, while the seismic isolation effect under the far-field long-period ground motion is far worse than that under the ordinary ground motion. The foundation and the isolation layer have an obvious rotation effect, and the isolation layer has a certain amplification effect on the rotation of the foundation. The amplification effect is more obvious under the far-field long-period ground motion than that under the ordinary ground motion, which is related to the larger response of far-field long-period ground motion to the displacement of the isolation layer.