###### Abstract
The inertial force applied to the mass was tuned through a series of conversions and signal processing to ensure force equilibrium between the two substructures. [PERSON] et al. [31] presented a general formulation of the RTHS with a combination of the numerical computation and physical specimens excited by shake tables and auxiliary actuators. Dependent on the available testing facilities and their capacity, this hybrid simulation method can be executed for real-time pseudo-dynamic testing, dynamic testing, or a combination of both. To perform a dynamic analysis of a complex NS, the finite element method was incorporated into the Simulink model through the S-function [32]. This system was applied to study the dynamic behavior of the soil-structure interaction, where the shear frame is excited by a shake table while the foundation is simulated as a finite element model with 132 degrees of freedom. [PERSON] et al. [33] described the design and implementation of STST hardware and software architecture. Their architecture has also been developed and verified based on an educational electromechanical shake table extensively used in over 100 countries worldwide [34]. [PERSON] et al. [35] compared the performance of three commonly used delay compensation schemes for real-time dynamic substructuring with a shaking table as the transfer system in terms of accuracy and stability. It was concluded that delay compensation can decrease test accuracy and stability. [PERSON] et al. [36] performed a comprehensive investigation of the stability of the STST system based on two model-based integration algorithms with controllable numerical energy dissipation. Studies have shown that the mass ratio, frequency ratio, and time step have an adverse influence on the stability of the STST system. A series of substructure shake table tests were conducted to validate the effectiveness of particle dampers on the reduction of structural seismic responses in [PERSON] et al. [37]. The effect of the soil-structure interaction on the performance of a passive structural control strategy was examined through multi-site experiments using two shake tables [38]. The test results revealed that the passive control strategy designed without considering the soil dynamics was clearly compromised. RTHS was implemented to investigate the size effect of TLDs [39]. It was found that conventional shaking table tests (STTs) with scaled TLD models generally overestimate the control performance of prototype TLD devices, thereby indicating the advantages of RTHS with a full-scale TLD. RTHS was employed for seismic performance evaluation of a 14-story building with inter-story isolation [40]. The substructure below the isolation layer was simulated numerically, while the superstructure above the isolation layer was tested experimentally. [PERSON] and [PERSON] [41] implemented a three-variable control (TVC) to an existing hybrid simulation system, which was adopted for RTHS of electrical disconnect switches on a shaking table configuration. [PERSON] et al. [42] conducted real-time substructure shaking table testing of an equipment-structure-soil system to study the effects of soil on the seismic energy responses of the equipment-structure subsystem. The branch modal substructure approach was employed to derive the formulas needed for the real-time substructure shaking table testing of the equipment-structure-soil system. [PERSON] et al. [43] implemented real-time substructure shaking table testing on equipment-structure-soil systems with different connection types to analyze the effects of soil on the energy response. In our study, the RTHS is combined with a sophisticated shake table as the transfer system and is named as STST. This literature review shows that some issues and challenges regarding STST must be addressed to enable its wide application. The control accuracy of the shake table is a significant challenge.