## 5 Numerical Simulations
It can be seen from the figure that, compared to non-pulse-type near-fault earthquakes (type C) and far-field earthquakes(type D), pulse-type near-fault earthquakes (types A and B) can cause much larger inter-story drifts and floor accelerations at the bottom and center of SHFLC isolated structure, and this will decrease gradually with the height of the floors. It is also noted that, for the type C near-fault earthquakes, the peak inter-story drifts and floor accelerations at the top of the isolated superstructure exceed the corresponding values of the pulse-type near-fault earthquakes. For the pulse-type near-fault earthquakes, the earthquakes containing fling-step effect (type A) can induce much larger responses of the SHFLC isolated superstructure excepting at the bottom floor. In addition, far-field earthquakes (type D) have a minimal influence on the inter-story drifts of SHFLC isolated superstructure. To explore the influence of pulse-type near-fault earthquakes on base displacements, the peak base displacements of SHFLC isolated structure under four types of earthquakes are shown in Figure 9. It can be seen from this figure that the peak base displacements of SHFLC isolated structure are less than 0.2 m for most of the pulse-type near-fault earthquakes. For the two types of near-fault earthquakes with the fling-step effect and the rupture forward directivity, the average peak base displacement is 0.167 m and 0.187 m, respectively. However, the base displacement decreased was evident when subjected to non-pulse-type near-fault and far field earthquakes, with the average peak base displacements equal to 0.065 m and 0.046 m, respectively. It can be concluded that pulse-type near-fault earthquakes can lead to much larger responses for SHFLC isolated structure as compared to non-pulse-type near fault earthquake and far-field earthquake, especially in the isolation layer and the bottom of the superstructure. Figure 8: Average peak inter-story drift and floor acceleration of controlled base-isolated structure subjected to earthquakes: (**a**) average peak inter-story drift; and (**b**) average peak floor acceleration. The performance indices for the pulse-type near-fault earthquakes and the earthquakes without pulse-effect are listed in Tables 7 and 8, respectively. In these tables, the self-tuning hierarchic fuzzy logic control strategy is named SHFLC. Moreover, for comparison, the results for the maximum passive operation of PFDs are also listed in these tables. Numbers in bold font indicate the best results among the two control cases for the given excitations. Base displacement is an important index to evaluate the effectiveness of the proposed control strategy. For a base-isolated structure subjected to pulse-type near-fault earthquakes, one of the primary purposes is to prevent permanent damage on the isolation bearing or collision with adjacent structures. In these tables, it can be seen that although the maximum passive operation of the PFDs can successfully reduce the performance indices associated with the peak and RMS base displacements (\(J_{3}\) and \(J_{7}\)), it will lead to significant amplification in peak and RMS floor acceleration (\(J_{5}\) and \(J_{8}\)) for most of the selected earthquakes due to the large constant damper force. For pulse-type near-fault earthquakes, such as A1, A4, B1, B2, and B4, the maximum passive operation of the PFD increases the peak floor acceleration by 40%, 74%, 31%, 52% and 33%, respectively, compared to the uncontrolled structure. However, for the earthquake without pulse-effect, the maximum passive operation of the PFD caused an increase in the responses compared to the uncontrolled structure, except for the C4 earthquake. The increase in peak acceleration (\(J_{5}\)) for C1, C2, C3, D1, D2, D3, and D4 are 48%, 29%, 42%, 17%, 37%, 22% and 39%, respectively.