Analysis for Displacement Response Characteristics of Complex Multi-layer Base-Isolated Structure under Near-Field Ground Motion

In order to study the influence of near-field ground motion characteristic parameters on the seismic displacement response of a super-long complex base-isolated structure, firstly the correlation among 128 near-field ground motion characteristic parameters was analyzed. Then, the near-field ground motions were inputted into the super-long complex base-isolated structure. The correlation degree and variation characteristics between the characteristic parameters of impulsive and non-impulsive ground motions and structural displacement response were analyzed. The results show that the long period of the base-isolated structure is close to the velocity sensitivity range in the velocity spectrum, but far from the acceleration sensitivity range in the acceleration spectrum, such that the displacement response is more correlated with the peak ground velocity (PGV) rather than peak ground acceleration (PGA). The peak ground displacement (PGD) and input energy have greater influence on the inter-story displacement of lower floors than on that of higher floors, while the PGV and PGA have less influence on the inter-story displacement of lower floors than on that of higher floors. The correlation degree between other characteristic parameters and the inter-story displacement response of the base- isolated structure is consistent with the correlation degree between the corresponding characteristic parameters and input energy (or PGV). Under the near-field earthquake, the displacement of the isolation bearing at the end and corner of the structure is obviously larger than that at the center. Impulsive ground motion magnifies the inter-story displacement and isolation layer displacement by 56.59% and 58.33% respectively, and the magnification effect on the inter-story displacement of lower floors is more obvious.