**6. Conclusions**

Real-time hybrid simulation is a powerful technique to evaluate the structural performance under dynamic loads, especially for structures with velocity- or accelerationdependent components. Due to the inherent nonlinearities of the servo-hydraulic actuator and the uncertainties in the systems, the boundary conditions between the two substructures could be realized completely. Hence, a mixed sensitivity-based *H* ∞ control method was proposed for RTHS. The main conclusions that could be reached are as follows.


However, it should be noted that the proposed method was only validated via a linear elastic specimen, and a nonlinear physical substructure should be used to further validate the feasibility. Furthermore, as the *H* ∞ controller is still a feedback controller in essence, the time delay cannot be eliminated. Hence, it is necessary to combine the *H* ∞ controller with other strategies.

**Funding:** The Scientific Research Fund of the Institute of Engineering Mechanics, China Earthquake Administration (Grant No. 2020D14), the National Natural Science Foundation of China (Grant No. 51908231), and the Natural Science Foundation of Fujian Province of China (Grant No. 2020J01058).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Conflicts of Interest:** The author declares no conflict of interest.
