Seismic Performance Analysis Of Diagrid-Core Tube Structure Based On Shaking Table Test

Diagrid-core tube structure is a new type of complex high-rise composite building structure,Because of the visual impact of its special external modeling and the huge stiffness of the outer tube,it was used frequently in the high-rise building structure nowadays,and very popular with designers,Shenzhen Rural Commercial Bank Building adopted this high-rise building structure system.But this kind of structure system is different from the traditional frame-tube structure.The cross-arranged inclined column of the outer tube replaces the traditional column,and the vertical and lateral loads of the structure are borne by its axial force,so there are many significant differences in the force path of outer tube and the failure mode between them.At present,this kind of structures are lack of seismic damage data,and the research on the structural response under earthquake action is not deep enough,so it is necessary to intense research on the seismic performance and force analysis of the structures.In this project(Shenzhen Rural Commercial Bank Building)the outer tube adopts the equal-angle inclined column,and this structure exceed the limit in many cases: the inclined column of outer tube is not connected with the peripheral beam of floor;different from other inclined column grid structures,there is no horizontal ring beam between the inclined columns;there is no floor between the four floors at the bottom of the structure,and the inner and outer tube are independent systems.In order to ensure the safety and reliability of the complex structure under earthquake action,the mature,direct and reliable shaking table test method and finite element numerical simulation analysis method are adopted to carry out a systematic and in-depth research on the seismic performance of the structure.At first,In this paper,based on the prototype structure of Shenzhen Rural Commercial Bank Building,a scale test model with a geometric similarity ratio of 1:20 is designed and made according to the similarity theory,and a simulated seismic shaking table test is carried out at the Earthquake engineering center of Guangzhou University.Using three seismic waves(one artificial wave and two natural wave)provided by the owner as the input excitation,the test carried out a total of 38 unidirectional and multi-directional loading conditions under the action of different level intensity of 7 degrees frequent earthquake,7 degrees of basic earthquake and 7 degrees of rare earthquake,and the acceleration sensor and the strain sensor are arranged in the response position of the model structure.The dynamic characteristics of the model structure,the basic dynamic response(Floor acceleration,floor displacement,floor torsion,inter-story drift,etc.)and the strain at the key bearing force part of the model structure were measured,the crack distribution of the inner tube shear wall and floor slab of the model structure and the failure mode of the inclined column of outer tube are investigated.According to the macroscopic failure phenomenon of the test and the change of dynamic characteristics of the model structure before and after the earthquake with different levels of intensity,it is shown that,after the seismic action with different leveling intensity,the frequency of each modal of the structure shows a downward trend,and the structure enters the plastic state.The buckling failure of compression was observed in partial component of variable cross section of the inclined column of outer tube,and the horizontal crack appeared in the upper floor shear wall limb of the inner tube at the same time.The horizontal deformation of the structure along the direction of the height of the structure is basically an inverted triangular distribution model.the structure has good seismic performance.Secondly,based on the software of OPENSEES,the nonlinear model of prototype structure is established.By comparing the experimental results with the finite element calculation results,it is shown that the dynamic response of the model is consistent with the trend,and the error is within the acceptable range,which verifies the correctness of the finite element model.On this basis,in order to further study the cooperative working performance of the inner and outer tube of the structure and the failure path of the inclined column of outer tube,Analysis the finite element model by Pushover method.In the aspect of the cooperation of inner and outer tubes,the results show that the inclined column of outer tube is the main anti lateral components of the structure,and with the increase of the structure's deformation,the proportion of the shear in each layer of outer tube increases gradually.At the same time,the stiffness of inclined column of outer tube will decrease rapidly when the stiffness is reduced to a certain extent.In the aspect of the yield path of the outer tube,the inclined column of the outer tube is the potential weak link of the structure at the variable cross section,and then the inclined column develops from the initial failure floor to the upper and lower floors,while maintaining the trend of developing towards the middle elevation of the failure layer.On the whole,it shows strong spatial stress characteristics.