Virtual Spring Method for Improving Accuracy in Real-Time Hybrid Testing of Reinforced-Concrete Structures

Real-time hybrid testing (RTHT) is an experimental technique for efficiently analyzing the dynamic responses of seismic structures. Since most parts of the tested structure are numerical simulated and only selected structural components are physically tested in RTHT, the costs and actuator power demands of RTHT are considerably lower than those of a shaking table test. Nevertheless, the actuator control commands in RTHT are typically calculated within the numerical substructure, and the actuators must follow these commands in real time to ensure the accuracy of the RTHT test results. Therefore, the actuator’s dynamic performance is a critical issue in RTHT, as deficiencies in actuator performance can significantly affect the accuracy of experimental results. To minimize the influence of inadequate actuator performance on the accuracy of RTHT, this paper proposes a control compensation method called the virtual spring method. To verify the proposed method, RTHT of a seven-story RC building utilizing the virtual spring method is conducted to compensate for the degraded actuator performance and the results are compared with theoretical responses. A comparison between the RTHT and the theoretical results reveals only a minute difference between the two results. Thus, this study demonstrates that the proposed virtual spring method is an effective approach for stabilizing the control system and mitigating the effect of control error on the accuracy of RTHT results.