Study On Vibration Control Of Free-Standing Cultural Relics

Earthquakes are one of the main disasters that lead to the destruction of free-standing cultural relics.In recent years,the research on seismic isolation protection of cultural relics has gradually attracted the attention of seismic engineering researchers.As the protection of cultural relics is one of the important measures for the protection of cultural heritage,it is particularly important to study the seismic protection of free-standing cultural relics in museums.Based on the achievements of many scholars and researchers at home and abroad,this paper puts forward a new type of isolation bearing for cultural relics in view of seismic safety performance and response control strategy of seismic system for culture relics.Through theoretical analysis and static test,the double-flag hysteretic model,correlation between parameters and design methods of the new type of isolation bearing for cultural relics are studied.What’s more,the shaking table test of the new type of isolation bearing for cultural relics is carried out.Finally,the isolation design and seismic response analysis of free-standing cultural relics in a museum under earthquake are calculated by examples.The main research work and achievements are as follows:(1)This paper establishes the dynamic equation of free-standing cultural relics,takes certain seismic redundancy,calculates and analyzes the acceleration limit value of anti-overturning of free-standing cultural relics.The isolation systems of exhibition cabinet and free-standing cultural relic bearings are studied respectively.The double-mass and three-particle models,whose substructure of the stiffness and mass are much less than that of their main structure,are establishing to prove that the dynamic characteristics of the main structure and its substructures are decoupled whether the substructure is placed on the top floor or on other floors.And the decoupling of the dynamic characteristics of the main structure and the substructure are proved by themulti-degree-of-freedom analysis model.This paper develops successively response spectrum analysis tools and floor spectrum analysis tools,and summarizes basic laws of floor spectrum through proof of decoupling.(2)A new type of isolation bearing for cultural relics is proposed.It achieves the restoring ability of the non-linear elastic segment by preloading spring and realizes energy dissipation by friction sliding,which can overcome the problem of starting the isolation system for cultural relics and solve the starting problem of the vibration control of free-standing cultural relics under micro-vibration.By means of theoretical analysis and model test,the mechanical properties of the new type of isolation bearing for cultural relics are systematically studied.The double-flag hysteretic restoring force model of the new type of isolation bearing for cultural relics is constructed,and the results of relevant hysteretic test verify the feasibility of the proposed new type of isolation bearing for cultural relics and the correctness of the hysteretic model.In shaking table test,the results show that the device does not start when the input seismic acceleration is small,but the isolation effect of the isolation device is more obvious when the input seismic acceleration is large.Furthermore,by comparing with the numerical simulation method,the result shows that vibration response laws of the device surface obtained by numerical simulation are consistent with the that of experimental analysis.(3)This paper discusses the displacement prediction of floor pseudo-velocity spectrum and cultural relic isolation bearing under inputs of different pseudo-velocity spectrum.What’s more,the seismic performance targets of free-standing cultural relics are determined by two and three particle models.And the amplification multiple of pseudo-velocity spectrum of each particle are calculated and determined according to a large number of artificial waves.By exploring the calculation and application of the energy prediction method as well as the equivalent linearization prediction method in the isolation bearing of cultural relics,the recommended reference values of the design parameters of the isolation bearing for cultural relics are determined under conditions ofamplitude inputs in different pseudo-velocity spectrum.As well,the prediction results of the two methods are compared,which shows that they are basically consistent.(4)The accuracy and convenience of the analysis tool V3.0 of floor response spectrum are verified by the modeling of YJK/ETBAS.The vibration time history of each floor obtained by the floor spectrum analysis tool V3.0 is used to input into the isolation bearing of cultural relics.The model is modeled and analyzed by SAP2000 finite element analysis software for the isolation bearing structure of cultural relics,which is double-flag hysteretic model stimulated equivalently by combining Multilinear Elastic cell and Friction Isolator cell.According to the above operation,the results show that the greater the peak acceleration of the floor is,the better the effect of shock absorption is,the greater the rate of shock absorption is,and the decreasing amplitude ratio is as high as82.29%.By comparing the results of force-time history method and equivalent static method(energy method and prediction method of equivalent linearization),the comparison results are in good agreement,which shows the accuracy and validity of the dynamic time-history calculation.