The Application And Energy Dissipation Research On Large Height-width Ratio Base-isolated High-rise Structures

As the research of solation technongy continues,the isolated structure is toward high-rise and complex building forward.However,the study about the seismic reduction effect of isolated high-rise structures is insufficient.In addition,there is yet no unified understanding about the vibration reduction mechanism of isolated high-rise structures.In this study,the isolation layer design for a large aspect ratio high-rise shear wall structure is carried out.The elastic analysis under the mediate-earthquake and major-earthquake are conducted respectively.In addition,the vibration-reduction forms of high-rise isolated structures are investigated via the analysis of the energy dissipation.The main research results are listed below:In order to solve the problem about the large tensile stresses of the rubber bearings used in large height-width ratio isolated buildings and the risk of structures overturning,the study about the thick plate transition isolation layer applied to high-rise shear wall structure is conducted and the new bearing programs are proposed.In addition,the medium and sever earthquake equivalent elastic analysis in basic model is carried out.The obtained results indicate that the uniform bearings compressed stress,decreased probability of bearing in tension,and enhanced capacity of anti-overturning could be presented when the large diameter and spacing bearing programs is adopted under the thick plate transition layer.After being isolated,the structural natural periods is increased by 0.85-fold.And the seismic decrease coefficient is 0.43.Thus the fortification criterion of upper structure could be reduced by half a degree.In this thesis,the influence of different height-width ratios,site classifications and defense intensity on the isolated high-rise structures is analyzed.It is found that the effects on the value of bearings tensile stress,the number of tensile stress bearing,seismic decrease coefficient.In the IV site,the structural displacement of isolated high-rise buildings is maximum and the seismic decrease coefficient is minimum.In addition,the higher the fortification intensity is,the more obvious the character of bending deformation in the upper structure can be found.Meanwhile,the capacity of anti-overturning is decreased as the functions of the enhanced fortification intensity.This work is focus on the elastoplastic analysis and energy dissipation under major earthquake.The responsiveness of isolation layer and the damage to the upper structure under the major earthquake are analyzed.The obtained results show that the acceleration response between the high-rise isolation structure layers presents K-distribution.Moreover,the tension crack in the shear wall of storey around isolation layer is observed.In general,the hysteretic energy consumption of isolated structures is as much as that of structural mode.The isolation bearing hysteretic performance and the high-rise isolation structure acceleration response reflect the energy consumption of isolation structure layers.Therefore,the improvement of bearing energy dissipation efficiency can enhance the energy consumption ratio of isolation structure layers and decrease the seismic response of the upper structures.In this study,the comparative analysis about the filtering effect of isolated high-rise structures via extracting “filtering time-history record” is conducted.The changes of earthquake energy before and after the isolation layer are characterized via the power spectral density function.The obtained results are consistent with seismic reduction effects of isolated high-rise structures,further confirming the “energy filtering” theory.