Seismic Design And Elastoplastic Timing Analysis Of A Double-tower Connected Structure

A conjoined building is a building with connecting body between two or more towers.Because of its characteristics of facade modeling it is favored by architects in recent years.However,such conjoined designs bring forth many challenges for structural engineers.This paper illustrates an exemplary connected double-tower building and describes in detail the seismic design and behavior of its structure in case of a frequent earthquake,a intermediate earthquake,and a severe earthquake.The results lead to corresponding measures for seismic performance-based design which in turn provide reference for similar building structures.The project revolves around a two 23-story,97.4 meters high frame-core tube construction.The structure is linked via a 34.9~45.9 meter truss connection between the 22 nd and 23 rd floors.A truss located at the 21 st floor supports the 22 nd,while the 19 th and 20 th floor harbor a tower span suspension truss structure.This particular complex type of structure,conform the current standard,demands for specifically high requirements: irregular torsion,floor discontinuity,stiffness mutation,vertical component discontinuity,and cross-floor column.Main structure analysis:1.In a frequent earthquake scenario,spatial analysis programs of two different mechanical models are applied to a calculate and analyze the SATWE software(simplified wall element Model,2010 edition),compiled by China Academy of Architectural Sciences.The structural calculation takes into account accidental eccentricity,bidirectional seismic activity,torsion coupling and construction simulation.The elastic time history analysis program is used to make a supplementary check on the seismic activity of buildings.The calculated results of the two softwares show that the dynamic characteristics of the structure are consistent,the performance indexes of the structure are close to the calculation,and the structure of the computational analysis is reasonable and reliable.2.The elastic time history analysis program is used to perform a supplementary check on the seismic action of the building.The results show that the time-history analysis of each seismic wave is similar to: the elastic inter-story drift ratio curve;the average bottom shear ratio meets the requirements the shear force of the connected structure is larger;the average shear force at the top of the tower is slightly larger than the response spectrum's;and the maximum value is taken in design under frequent earthquake.3.Under rare earthquake,the dynamic elasto-plastic time history analysis is carried out.The analysis results show the effects of each seismic wave under the maximum elasto-plastic inter-story drift ratio is 1/163.meeting the requirements of specification.There is no obvious mutation in between the inter-story drift ratio curve of the structure.The columns of the structure have no damage under rare earthquake,while the connection of the shear wall and coupling beam endure slight damage.The coupling beam completely exerted the energy dissipation,showing the seismic energy dissipation mechanism is reasonably sufficient.According to the calculation results,seismic measures are proposed.4.The connecting parts are complex and are considered ‘difficult construction' according to existing construction technology.The construction simulation and stress analysis of the two conventional construction schemes respectively,show that the maximum stress of steel structural components is not more than 256 MPa while stress ratio is less than 1.0 during construction,guaranteeing the safety of the components.5.Comfort checking calculation was taken and the results meet the requirements.6.Stress analysis of the connecting floor temperatures display large stress,apart from the upper floor.To meet the requirements,it is necessary to improve the ratio of reinforcement to strengthen the structure.Rest of layers are able to meet the requirements.Results of the stress analysis on vertical load,earthquake action and wind loads show the effect of the truss on the upper and lower floors.The maximum stress exceeds the standard concrete cracking stress,meaning the reinforcement must be strengthened.7.As the main load transfer member,A finite element analysis of the main force component with ANSYS software shows that,under different working conditions,the node area can meet the performance requirement.8.The continuous collapse analysis of the connected truss was accomplished with the method of demolition component.The analysis results show the realization of internal redistribution of force,while the stress ratio of each component is less than 1,meeting the specification requirements.