Optimization Design Analysis Of Vertical Irregular High-rise Frame Core Tube Structure

In recent years,with the rapid development of China’s economic construction,high-rise buildings have gradually become the core development trend in the construction field.In order to meet the requirements of building functional diversity under different working conditions,the structure of high-rise buildings is gradually diversified and complicated.In order to make full use of the building space,each floor often adopts the way of different storey height,which directly leads to the irregular distribution of lateral stiffness of the whole structure.Frame core tube structure is one of the common structural systems of high-rise buildings.The inner core tube and the outer concrete frame form the outer frame inner tube structure,which has the advantages of flexible use space,good economy and superior seismic performance.The engineering example of this paper is selected from the construction project of engineering application practice base of Jilin Institute of chemical technology.The second floor of the structure is used as the engineering practice simulation center.After it is put into use,large equipment with various loads and heights exceeding the design range of normal building structure needs to be placed.The floor height is up to 8.7m,which is much higher than the floor height of adjacent buildings,resulting in sudden change of floor height of the structure.In this paper,the optimal design scheme for this kind of vertical irregular frame core tube high-rise building structure is proposed,the seismic performance is studied by using PKPM structural analysis software,and the finite element analysis is carried out by using ABAQUS software.The main research contents and conclusions are as follows:（1）The seismic performance of the original design scheme under elastic state is analyzed by using PKPM structural design software,and the parameters such as period,displacement,displacement angle,stiffness weight ratio,shear weight ratio,floor lateral stiffness ratio and shear bearing capacity ratio are given.At the same time,the model is established by ETABS structural analysis software and compared with the calculation results of PKPM.The results show that the sudden change of the height of the second floor of the structure leads to the small lateral stiffness of the floor,and the floor stiffness ratio is less than 1.The analysis shows that the change of the lateral stiffness of the structure is discontinuous,and the second floor of the structure is a weak layer defined in the code.At the same time,the structural displacement ratio exceeds 1.2,indicating that the structure is prone to torsion or displacement under the action of earthquake,and the torsional effect of the structure can not be controlled.（2）The optimization design scheme of adding column bracing on the second floor of the structure is proposed.The analysis of the optimization scheme by using PKPM software shows that the optimization scheme increases the stiffness ratio of the second floor of the structure to1.19,eliminates the existence of weak layers in the structure,and reduces the displacement ratio of the structure.According to the elastic time history calculation,the x-direction base shear of the structure in the optimization scheme is 9972.24 k N,and the y-direction base shear is 11084.24 k N,and the floor shear results are enveloped by the results obtained by the response spectrum method.The results show that the overall stiffness of the structure is increased in the optimization scheme,the anti deformation ability of the structure is increased in the optimization scheme,and the seismic capacity of the structure is optimized.（3）The optimization scheme analysis model is established by using ABAQUS software to carry out the finite element analysis of frame beam column and shear wall floor.According to the modal analysis results,the first three vibration modes of the structure are X-direction translation,Z-direction torsion and Y-direction translation respectively.Under three different working conditions,the maximum interlayer displacement angle in X direction and Y direction is 1/2509 and 1/3597 respectively.Then,the stress-strain responses of the frame and shear wall are compared and analyzed.It can be seen more intuitively that the inter column support stress applied by the optimization scheme is the most significant under the action of earthquake.The support components obviously participate in the internal force distribution of the whole building and resist more loads.The optimization scheme makes the whole building more stable.The optimization design method of adding inter column support in vertical irregular floors proposed in this paper has a certain reference value for the design and application of similar projects.