Numerical Simulation Analysis And Adaptive Delay Compensation Method For Real-time Hybrid Simulation Of Seismic Isolation Structure With High Damping Rubber Bearings

Seismic isolation technique has been recognized as one of the most widely implemented and accepted means of structural seismic prevention owing to its advanced concept and reliable performance.As one of the widely used seismic bearings,laminated rubber bearings have been investigated by many researchers.The high damping rubber bearing(HDRB),an innovative laminated rubber bearing,is increasingly popularized by virtue of its addition of damping and environmental-friendly characteristics.However,its complex nonlinearity and rate-dependent behaviors are difficult to accurately describe with traditional numerical models,which affects the performance-based seismic design and assessment of seismic isolation systems.The realtime hybrid simulation(RTHS)combines the advantages of executing the physical substructure(PS)under realistic seismic loading conditions and simulating the remainder of part as numerical substructure(NS)in high-efficiency.RTHS can evaluate the dynamic performance of components and devices that are under full-scale conditions and/or sensitive to loading rate(e.g.,seismic isolation bearings).However,it has been previously shown that time delay due to inherent dynamics of servo-hydraulic actuator creates negative damping that can be detrimental to the accuracy and stability of the entire experiment and even cause damage to the devices and equipment.In this paper,the rate-dependence of HDRB is investigated based on RTHS.A ratedependent mechanical model of HDRB is established through experimental research and numerical simulation,and an adaptive time delay compensator is proposed for the time-varying delay.At the same time,virtual RTHS of an isolated structure with HDRB is carried out.The main research contents and corresponding conclusions are as follows:(1)Starting from the selection criteria of the isolator model,based on Bouc-Wen model,combined with the law of change between model parameters and the shape of the hysteresis curve,and sensitivity analysis of bearing parameters to the loading rate,and considering the parameters n polynomial fitting on the loading rate,a rate-dependent mechanical model of HDRB is established.A simulation analysis of the rate-dependent mechanical model under the excitation of sinusoidal signals and earthquakes is carried out.It is found that the mechanical behavior of the bearing described by the new model can be very close to the true value of the model,which shows the correctness of the proposed HDRB model.Based on the mechanical performance test of HDRBs,the rate-dependent mechanical model was identified,and the results showed that the test results fit the bearing model well.(2)The variable forgetting factor recursive least squares(RLS)algorithm is introduced into the RTHS.An adaptive time delay compensation method is proposed,and the performance of the compensator is executed based on the Benchmark control problem for RTHS.The adaptive time delay compensation method adjusts the forgetting factor based on the system error,identifies model parameters,and compensates the time delay.The results show that the maximum evaluation criteria J1～J3 on the nominal system are 0ms,2.01% and 2.81%,respectively,which demonstrates a good tracking performance,fast convergence,high accuracy,and robustness to noise.(3)Based on the rate-dependent model in Chapter 2 and the adaptive time delay compensation method in Chapter 3,numerical simulation analysis for RTHS of a seven-story base-isolated frame structure is established.After solving the equations of motion for NS,analyzing dynamic performance of the transfer system,and designing and implementing compensator,the dynamic responses of seismic bearings and superstructure are obtained.The research results show that time delay of transfer system reduces from 30 ms to around 1.9ms,which demonstrates the accuracy and robustness to noise,uncertainties,and dynamic performances of the transfer system.The accurate numerical simulation analysis provides a theoretical and simulation basis for using RTHS to evaluate the rate-dependence property of HDRBs under realistic earthquake excitations.