Study On Seismic Performance Of Frame Core Tube Structure With High Truss Conversion Layer

In recent decades,high-rise buildings have developed rapidly,and the structural design with conversion layer is more and more favored,compared with the common beam conversion structure,truss conversion structure has the characteristics of large space,clear force transmission path and small self-weight.At present,some studies have been done on the seismic performance of truss conversion structures in China,but there are not many studies on the impact of high truss conversion layers,especially different truss forms,on the seismic performance of high truss conversion layer structures.Therefore,this paper analyzes the seismic performance of the core tube structure of a high-level truss conversion layer frame,and the specific content is as follows:(1)First,the finite element software PKPM and Midas Gen were used to analyze the modal analysis and reaction spectrum analysis of the core tube structure of the frame of the high-level truss conversion layer,and the differences in the analysis results of the two software were compared.Then,on the basis of verifying the correctness of the model,the elastic time history analysis of the structure is carried out,and the calculated data is compared with the response spectrum results.Finally,the elastoplastic time history analysis of the structure is carried out to verify the feasibility of the building structure.(2)Under the condition that the amount of truss material is unchanged and the cross-sectional size of truss is unchanged,the core tube structure of the high-level truss conversion layer frame with herringbone oblique truss,hybrid truss,cross oblique truss and fasting truss is analyzed by response spectrum analysis and elastic time history analysis,so as to obtain a better truss form.From the reaction spectrum calculation results and time history analysis data,it can be seen that the herringbone oblique truss truss conversion layer structure has greater stiffness and smaller structural deformation than other truss forms under the condition that the amount of truss material is unchanged,which indicates that the herringbone oblique truss truss form is a better choice in this case.Under the condition that the cross-sectional size of the truss is unchanged,the minimum stiffness ratio of the cross-oblique truss conversion layer structure and the hybrid truss conversion layer structure does not meet the specification requirements,while the herringbone oblique truss structure has greater rigidity,smaller structural deformation and little material increase than the fasting truss structure,so the herringbone oblique truss form is still better in this case.Based on the above two situations,the herringbone oblique truss truss structure is better.(3)In the case of high position,the superior herringbone oblique truss form obtained by the above analysis is selected,and four herringbone oblique truss conversion models with different conversion layer positions are established,and the response spectrum analysis and elastic time history analysis are analyzed respectively,and the influence of different conversion layer positions on the seismic performance of the structure under the condition of constant structural layer height and total height is discussed.Comparing the results of seismic performance indexes,it can be found that under the condition that the floor height is unchanged,the rise of the position of the conversion layer increases the floor displacement and interlayer displacement angle of the structure.Under the condition that the total height is unchanged,the rise of the position of the conversion layer reduces the maximum floor displacement and the displacement angle between the floors of the structure.In both cases,the rise of the position of the conversion layer increases the internal force of the upward chord and oblique rod of the conversion truss X and the lower chord in both directions.However,the sudden change of floor shear force at the conversion layer was alleviated,and the internal forces of the upward chord and the oblique rod of the conversion truss Y showed a decreasing trend.Therefore,under the premise that all seismic performance indicators meet the requirements of the specification,for the condition that the layer height is unchanged,appropriately increasing the position of the conversion layer can alleviate the sudden change in shear force at the conversion layer and reduce the internal force of the upward chord and oblique rod of the conversion truss Y.For the condition that the total height is unchanged,appropriately increasing the position of the conversion layer can reduce the structural deformation and alleviate the sudden change of shear force at the conversion layer,as well as reduce the internal forces of the upward chord and oblique rod of the conversion truss Y.