Study On The Stability And Delay Compensation Of Real-time Hybrid Simulation For Shaking Table Test

Seismic analysis and research for engineering structure is a critical issue in the area of civil engineering.Real-time hybrid testing is one of the effective solutions to do this research.Real-time hybrid testing is a testing method which coupling the physical substructure that tested on-site and numerical substructure that calculated using numerical models in real-time.The real-time hybrid testing combines the advantages of fast computing ability of computer and powerful loading ability of servo-hydraulic system.Based on the servo-hydraulic system,a real-time hybrid testing platform for dynamic coupling is established,the time-delay and stability of a shaking table realtime hybrid testing system is introduced,and more detailed introductions and major conclusions are presented as the following:(1)Based on the servo-hydraulic actuation system,the lumped parameter model of foundation soil considering SSI effect is treated as the numerical substructure,and a real-time hybrid test platform considering the dynamic coupling effect is implemented.The feasibility of the platform is verified by a real-time test.The results show that the time-delay of the servo hydraulic system will affect the performance of the test,which should be compensated.(2)Based on the assumption of separation of time-delay,the system’s time-delay is divided into constant time-delay and variable time-delay,and a two-stage online iterative time-delay compensation method is proposed.Combining with the real-time calculation method of system time-delay,the numerical simulation and the real-time hybrid testing of bridge piers are carried out.The results show that the proposed timedelay compensation method has the characteristics of high accuracy and good stability.It can calculate the time-delay of the servo-hydraulic system online and has good performance.For the real-time hybrid testing platform,the high-precision compensation in the high frequency band above 10 Hz is realized.(3)Based on the Lyapunov-Krasovski stability analysis theory,the stability of realtime hybrid testing considering the dynamic coupling effect is analyzed.The critical time-delay of a time-varying time-delay system in the real-time hybrid testing is solved.Furthermore,based on the generalized Eigen matrix method,the critical time-delay of time-invariant system in the real-time hybrid testing is calculated exactly.The results show that the faster the time-delay of servo-hydraulic system changes,the more unstable the real-time hybrid testing is.(4)Based on the stability theory of amplification matrix,considering the interaction between the stability of integral algorithm and the time-delay of servo-hydraulic system,this paper presents an analysis process of the influence of time-delay of hydraulic system and numerical integration algorithm on the stability of real-time hybrid test.