Shaking Table Experimental Research On The Single-tower Isolated Structure With Large Chassis

Single-tower structure with large chassis using isolation technology can effectively solve the problem of structural vertical rigidity mutation caused by building plan indentation.There are two forms of isolation layer,that is intercalating in the bottom of tower(story isolation)and intercalating in the bottom of chassis(base isolation),a large number of numerical simulations were conducted on these.two types of structural forms in domestic and foreign literature,and seismic response of these two types of structure was grasped preliminarily,while the validation by shaking table test simulating ground motion is very rare.Based on this,a single tower chassis system with engineering application significance was designed,the isolation layer is intercalated in the bottom of tower and chassis respectively,numerical analysis and shrinking scale shaking table tests for these two structural models are carried out.The main purpose is to get the seismic response of these two isolation forms,and to analysis and compare the differences of seismic response of these two kinds of isolated structure,then providing test data and engineering application recommendations for the seismic design of Single-tower isolated structure with large chassis.The main research work and achievements are as follows:(1)First,five-layer single tower structure model with large chassis is established,whose shrinking scale ratio is 1:7 and the plane area ratio of upper tower and lower chassis is 1:3.Three different acceleration peaks(0.20g,0.40g and 0.60g)earthquake action are set,and making numerical calculation by using finite element analysis software ETABS,the modal analysis and dynamic time history analysis of story isolation,base isolation and anti-seismic were conducted respectively,the analysis results showed that:1)The damping effect of tower structure acceleration,story displacement and story shear is significant in story isolation model above the isolation layer;2)acceleration response in the upper part of story isolation model has increased compared to the anti-seismic model,damping effect of story displacement and story shear were inferior to upper part of the tower;3)The damping effect of upper tower and bottom chassis are both significant.Based on the analysis results,seismic response characteristics of this single-tower isolated structure with large chassis is consistent with the numerical analysis of domestic and foreign related papers.(2)The steel test model as described above is made,and three structure models shaking table tests which are story isolation,base isolation and anti-seismic are conducted on it,27 working conditions of horizontal unidirectional shaking table test were carried out totally.The results of shaking table test are compared to the numerical simulation,and analysis results showed that:The calculation error between response of shaking table test and numerical is small,and they have high degree of agreement;The seismic response characteristics are consistent with the results of numerical simulation,which verifies the reliability of the numerical simulation results.(3)Composite numerical simulation analysis and shaking table test study shows that:upper tower damping effect are basically the same between base isolation system and story isolation system in large single tower chassis structure,while the damping effect of the lower chassis are quite different,the overall damping effect of the base isolation structure is superior to layer isolation structure.However,in engineering applications,due to the smaller area of upper tower and the larger area of lower chassis,base isolation form has higher costs,also,its isolated structural measures,construction and maintenance management is more complicated.Therefore,story isolation form is more suitable.