## 5 Control Performance Evaluation of the DQN Model
Two comparative semi-active control algorithms present contradictory performance in the decrease of the isolation story drift versus the 11 th-story drift. The isolation story drift controlled by the skyhook controller is the greatest among the three controllers, and the peak response occurs at around 8 s for both the EV1 and EV2 earthquakes. The peak isolation story drift of the DQN model is smaller than those of the two comparative controllers, as in the case of the previous 11 th-story drift. Figure 14: Comparison of the isolation story drift time histories: (**a**) responses to EV1, (**b**) responses to EV2. Figure 13: Comparison of the 11 th-story drift time histories: (**a**) responses to EV1, (**b**) responses to EV2. Figure 15: Comparison of the roof story displacement time histories: (**a**) responses to EV1, (**b**) responses to EV2. Figures 15 and 16 compare the roof story displacement and acceleration time histories of the three controllers. It seems that the peak roof story displacement of the groundhook controller is similar to that of the skyhook controller for EV1, but that of the groundhook controller is larger than that of the skyhook controller for EV2. The DQN model can effectively reduce roof story displacement, compared to the two comparative controllers for both EV1 and EV2 cases. In contrast to the displacement control performance, the peak roof story acceleration controlled by the DQN model is greater than that of the two comparative controllers for EV1. However, the DQN model controlled the peak roof story acceleration better than that of the two comparative controllers in case of EV2. The skyhook controller can effectively reduce the peak roof story acceleration compared to the groundhook controller. The control performance of the DQN model for seismic responses of the roof story is not consistent, compared to that for the story drift response reduction. This may be because the reward equation of the DQN model includes not the roof story responses but the story drift responses. In multi-purpose optimization, the optimization efficiency of each purpose generally decreases as the number of purposes increases. Therefore, if too many structural responses are included in the reward equation, the control performance of the DQN model may be disrupted. To quantitatively compare the control performance of each algorithm, Tables 3 and 4 list their peak responses. \"Passive\", in the control algorithm item, means the seismic responses obtained from the original Shiodome Sumitomo building with a passive mid-story isolation system. \"Passive-On\" or \"Passive-Off\" means the command voltage applied to the MR damper is kept constant at a maximum (5 V) or a minimum voltage (0 V), respectively. The ratio of each controlled response to the response of the original passive mid-story isolation system is presented in the corresponding parentheses. It is evident that most of the semi-active control cases provide better control performance than the original passive mid-story isolation system. A groundhook controller can reduce the peak isolation drift by 22% in comparison with the reference original passive model for EV1, while decreasing the peak 11 th-story drift by 6%. On the other hand, a skyhook controller reduces the peak 11 th-story drift by 12% in comparison with the original passive, maintaining the peak isolation story drift close to the original passive. A skyhook shows effective performance for the decrease of roof story responses in comparison with the other control cases, because it emulates the ideal configuration of a passive damper connected between the roof story of the structure and the sky, as shown in Figure 12a. Since the passive-on case provides the maximum MR damper force to the isolation story, the peak isolation-story drift is well controlled, compared to the other responses. In the passive-off case, the peak isolation-story drift significantly increases, because the minimum MR damper force is applied to the SMIS.