Research On Base Isolation Of Multi-tower Connected High-rise Building With Large Chassis

When the traditional seismic design is adopted for the multi-tower conjoined high-rise building in the strong earthquake area,the relative displacement between the towers under the action of the earthquake is too large,which often makes the conjoined building plan difficult to implement.It is hoped that this problem will be solved by adopting methods such as base isolation and conjoined flexible connection,which provide an effective way to enrich the forms of urban architecture in strong earthquake areas.This article combines the design scheme of a three-tower high-rise building with connector in a city located in a strong earthquake zone,aiming at using the measures of large-diameter isolation bearings(lead core bearings and skateboard bearings)to form the base isolation,the flexible connection between the tower and the connected body,etc.,to establish a finite element numerical simulation analysis mechanical model for 4 types,namely,large chassis multi-tower seismic structure,large chassis multi-tower base isolation structure,large chassis multi-tower base isolation structure with connectors,and large chassis multi-tower seismic structure with connectors.Using time-history analysis method,to consider three earthquake levels of frequent,fortification and rare,and three sets of three-way seismic record,the seismic response analysis of four models was conducted.By comparing and analyzing the results of the first two models,the seismic reduction effect after isolation of the structure is obtained;for the latter two models,we can get the effect on the towers after adding the connector.The following is the main conclusion of this paper:(1)Under the action of earthquake,the multi-tower high-rise seismic structure has obvious amplification effect on the acceleration of the floor,the relative displacement of the main and auxiliary towers in the connecting layer can reach 217.9mm,when the seismic wave acts unidirectionally under the rare level.So the relative displacement between the main and auxiliary towers at the height of the conjoined tower is too large to be connected.(2)The large-diameter lead core support and the skateboard support are combined to form an isolation layer,which has the characteristics of large horizontal limit displacement and moderate horizontal rigidity,which meets the needs of high-rise building isolation.When analyzing the impact of the sliding surface of the skateboard support on the friction force,it is necessary to consider the influence of factors such as self-weight and vertical seismic action on the normal direction of the sliding surface.(3)After the base isolation,the acceleration of each floor is significantly reduced,and the shock absorption rate is more than 54.66%;the earthquake amplification factor is also significantly reduced.Under the action of a rare earthquake,the maximum displacement of the isolation support is within the limit,and there is no tensile force at the corner of the support,which ensures the stability of the structure and does not cause overturning.The base isolation scheme for multi-tower high-rise structure with large chassis is feasible.(4)After base isolation,the relative displacement at the height of each tower to be connected is significantly reduced,after adding the connecting structure,the relative displacement of the structure is only 28.8%of the unconnected seismic structure,which creates conditions for the installation of connector.(5)After adding a flexible connection to connect the tower and the grid connection structure,it has little effect on the acceleration of the structural floor and the interlayer shear between the floors.The relative displacement between towers after isolation is within the limits of flexible connection.