Analysis Of Dynamic Characteristics And Seismic Performance Of Asymmetric High-rise Connected Structure

With the rapid development of China’s economy and the gradual decrease of land resources,high-rise buildings emerge in endlessly,and the improvement of building materials and construction technologies has caused more and more connected high-rise buildings to emerge.The connected building is to connect two or more buildings through the air connection,and place the space that can be shared by the two buildings on the connection body,which is convenient for the use of the two floors and solves the problem of horizontal connectivity between the two floors,make the monotonous building shape colorful.Therefore,the connected building is more and more favored by architects and developed rapidly,but the non-uniform rigidity of the connected building has also brought great challenges to structural engineers.Scholars at home and abroad have done a lot of research on the design of connected structures,and have achieved many results.However,due to the changes in the position and shape of the single building and the connecting body,most of the literature is focused on the research and analysis of the monolithic structure with symmetrical buildings on both sides,but the research on the asymmetric connected building is relatively rare.This paper takes an IT industry office building in Dalian as the research object to study the dynamic characteristics and seismic response of the asymmetric connected structure.The main research work and conclusions are as follows:(1)Using SAP2000 to establish the three-dimensional finite element model of the engineering example,the main calculation results under small earthquakes are similar to the calculation results of the original model of the engineering example,indicating that SAP2000 can be used in the review calculation of this project.The modal analysis of the results shows that: compared with the single structure and the symmetrical connection structure,the asymmetrical connection structure has obvious torsion coupling phenomenon,and the torsion effect is advanced.The first 16 vibration modes of the single tower and the first 30 vibration modes of the two towers all meet the requirement that the vibration mode participation coefficient is not less than 90%.The complexity of the connected structure determines that the vibration mode should be selected more than conventional buildings during engineering design.The natural vibration periods of the West Tower,East Tower,and Siamese structure are 2.4034 s,2.5101 s,and 2.3143 s,respectively.It can be seen that the West Tower natural vibration period decreases by 3.7% after the connection is added,and the East Tower decreases by 7.8%,indicating that the setting of the connecting body has a more obvious influence on the natural vibration period of the single tower with small stiffness.The results of variable parameter analysis show that: the connection method of the connecting body has little effect on the dynamic characteristics of the connecting structure.The position of the connector has a significant effect on the structure’s natural vibration characteristics,when it is located in the middle layer,the overall rigidity of the structure is large,and the natural vibration period is reduced,increased flat-twist coupling effect,not conducive to structural stress,and the closer to the top layer,the less obvious the torsion effect.The span of the connector has a slight effect on the natural vibration characteristics of the structure,increased span will slightly reduce the structural rigidity.(2)Select the design response spectrum,three seismic waves(El-Centro wave,Chi Chi wave and artificial wave)to carry out the response spectrum analysis and elastic time history analysis of the engineering example.Both analysis results show that the arrangement of the connecting body mainly affects the force and deformation of the structure in the X direction,but has little effect on the Y direction.Under the X-direction earthquake,the seismic response of the two single towers is close to the same,and the seismic performance indicators are close to 1: 1;when the Y-direction earthquake,the seismic response of the single tower with the larger volume is more obvious.For example,the maximum interlayer displacement angle of the west tower is 1.75 times that of the east tower.At the same time,the displacement angle between the floors of the double-tower connected structure meets the specification requirements,and the accuracy of the model is further verified by comparing the results of the time history analysis and the response spectrum analysis.(3)Change the connection mode,the position and span of the connection body,perform a variable-parameter elastic time history analysis of the model in the X direction,and compare and analyze the top layer displacement,top layer acceleration,interlayer displacement angle and base reaction before and after the parameter changes.According to the calculation results,it can be seen that the variable parameters have a large impact on the single tower with small volume,there is no difference between the rigid joint and the joint,the connection body is located on the top layer is beneficial to the structure,the connection body span should not be too small.At the same time,this article also compares the similarities and differences between the seismic performance and the deformability of the asymmetric connected structure and the symmetric connected structure.Finally,some practical suggestions are proposed in the engineering design of the asymmetric connected building,which can provide a certain reference for structural engineers.