Theory,Numerical Simulation And Experimental Investigation On The Inter-Storey Isolation Control Of Structures Based On Friction Pendulum System

Base isolation technology can effectively reduce the seismic response of the superstructure of the building,so that it will not be damaged or even collapsed when encountering seismic loads.Because the dynamic characteristics of high-rise structures are significantly different from those of multi-storey structures,the application of isolation technology in high-rise structures is limited.With the increase of the height-width ratio of the structure,the overall anti-overturning capacity reserve decreases,and the inter-storey displacement of the structure increases.It is difficult to achieve the expected effect by using the base isolation technology for high-rise structures.The control technology of inter-storey isolation based on friction pendulum system（FPS）applied to high-rise buildings is studied in this work with a view to the aforementioned issues.The vibration reduction mechanism,control effect influencing factors,and parameter influencing rules of the structure inter-storey isolation control based on FPS are thoroughly studied,and a design method for the FPS inter-storey isolation structure is suggested using a method that combines theoretical analysis,shaking table test,and finite element numerical analysis.The study’s findings can serve as a guide for high-rise structure isolation control.The following are the important research discoveries and successes:1)A numerical analysis of the FPS inter-storey isolation structure using MATLAB/Simulink is conducted,the mechanical mechanism of the FPS is studied,the motion equation for the FPS inter-storey isolation system is established,and the results of the simulation analysis for the FPS inter-storey isolation structure are provided.The analysis results show that the FPS inter-storey isolation control can reduce the floor acceleration response of the structure,limit the inter-storey deformation of the upper and lower structures,and consume seismic energy through the friction hysteresis of the FPS.2)The FPS used for the Quanser shaking table test is designed and manufactured.The refined finite element model of the FPS is established.The performance test of the FPS is carried out and compared with the finite element analysis.The results show that the designed FPS has full hysteretic curve and stable performance,which verifies the accuracy of the test model and the finite element model.3)A 1:18 nine-story steel frame high-rise structure with a height-width ratio of4.13.is designed and fabricated according to the consistent similarity relationship,using the FPS inter-storey isolation technology,based on the dimensional theory and comprehensively considering the bearing capacity of the laboratory shaking table and the test operation conditions.The shaking table test of high-rise structure with FPS inter-storey isolation is realized,and the capability of FPS inter-storey isolation control to resist large earthquakes is verified.The results show that when the FPS is set on the6^th–8^th floor of the structure,the top acceleration vibration reduction rate is 30%–67%.The vibration reduction effect is good under large earthquake conditions,and the isolation layer can recover itself.Through the analysis of the parameter influence law of the system,it is revealed that the working mechanism of the FPS inter-storey isolation control is similar to the Tuned Mass Damper（TMD）on the one hand.When the upper and lower structures generate relative motion,the inertial force of the upper structure plays a restraining role on the lower structure.On the other hand,the seismic response of the whole structure can be reduced by reducing the basic and higher-order mode components of the high-rise structure.4)The Ensemble Empirical Mode Decomposition（EEMD）method is applied to the signal processing of the floor acceleration response of the FPS inter-storey isolation structure,the contribution rate of each vibration mode in the overall acceleration response of the structure is studied,and the dynamic characteristics and parameter influence rules of the FPS inter-storey isolation structure are deeply revealed.The results show that in addition to the first vibration mode,the higher vibration mode of the FPS inter-storey isolation structure can also play a control role,which cannot be simply ignored.The position of the isolation layer plays a leading role in the influence of the dynamic characteristics of the FPS inter-storey isolation structure.As the position of the isolation layer moves down,the working mechanism of the FPS inter-storey isolation structure changes from the TMD tuning to energy dissipation,which is reflected in the change of the proportion of modal participation mass coefficient.5)The refined finite element model of the FPS inter-storey isolation high-rise structure and the uncontrolled structure is established and the parameter analysis is carried out.The results show that the initial stiffness of the FPS is changed by increasing the friction coefficient,the vibration reduction effect of the top floor acceleration increases with the increase of the friction coefficient,and the relative displacement of the FPS decreases accordingly;The increase of the slideway radius reduces the swing stiffness of the FPS,the top floor acceleration vibration reduction effect increases with the increase of the slideway radius,and the relative displacement of the FPS increases accordingly.The sum of the mass coefficients of the first and second modes after isolation is above 95%.The FPS inter-storey isolation tehnology adjusts the contribution proportion and distribution of each mode,effectively reducing the impact of higher order modes.6)A hybrid isolation control method based on FPS,combined with base isolation and inter-storey isolation is proposed.The shaking table test and finite element analysis of hybrid isolation control are carried out.The results show that the top acceleration damping effect of the hybrid isolation structure is above 56%.The working mechanism of the hybrid isolation FPS control is similar to the combination of TMD and base isolation.The inertia force of the upper structure plays a restraining role on the lower structure,while the lower structure is a base isolation form,which extends the structure period and hinders the upward transmission of seismic energy.The structural deformation can be distributed to the base isolation layer and the inter-storey isolation layer,which effectively limits the deformation of the isolation layer and avoids the problem of excessive deformation of a single isolation layer.