Study On Seismic Design Method Based On Expected Damage For High-rise Structure

At present,the seismic fortification goal of “no collapse under rare earthquake” can be achieved by the elastic-plastic deformation check of the weak floor of a structure based on the seismic conceptual design.However,it is difficult to identify the reasonable failure mode of the structure in the seismic design and ensure the formation of the reasonable failure mode.To solve this problem,it is urgent to develop a new seismic design for realizing the active control of the structural performance behavior under rare earthquake according to the predetermined failure mode.Therefore,it is necessary to define the reasonable predetermined failure mode,gain the expected damage of the component through the inversion from the overall damage of a structure and effectively implement the damage design for the component by introducing the component damage into the nonlinear seismic design of a structure,for providing a new design method to realize the active control of the structural failure mode.The specific research contents are as follows:Taking the failure mode of high-rise structure as the starting point,the damage evolution process of components were compared and analyzed based on different structural failure modes under the earthquake,and the patterns of damage distribution,damage sequences and damage degree of the structure were given to reveal the damage evolution rules.Based on the structural seismic concept,the relative damage relationships among components were compared and analyzed by introducing the weighted damage of components,and the influences of the relative damage relationships on the structural failure mode were determined to give the reasonable seismic failure mode of a structure.The inversion design of the expected damage was studied according to the reasonable seismic failure mode.The influencing factors of the relative damage relationship among components and the damage distribution along floors,such as axial compression ratio,bending stiffness ratio of column to beam,and integral coefficient of core tube,were analyzed to determine the control indexes.And the design principle of the damage inversion was proposed based on the damage weighting relationship between the structure damage and the component damage.Consequently,the design formulas of the expected damage inversion of a structure were given combined with the influences of the relative damage relationships among components and the damage distribution along floors on the damage weighting relationship,and an inversion design method was proposed eventually for gaining the component damage from the overall damage.The expected component damage was introduced into the seismic design to study the seismic design method.According to the relationship between the ductility of the damaged structure and the reduction of seismic internal force demand,a method for obtaining the nonlinear internal force demand for component was given based on the relationship.Meanwhile,the degradation law of the nonlinear mechanical performance was discussed according to the different failure modes of components,and the influencing factors and control parameters of the degradation of the component mechanical performance comprehensively analyzed to determine the reasonable controlling indexes.Consequently the quantitative relationship between the component damage and the degradation of the mechanical performance of the component was given to establish the seismic design method based on the expected damage,which implemented the damage design of the components and realize the active control of the structural failure mode.In order to verify the effectiveness of the seismic design method proposed in this paper,Two frame-core tube structure models were designed according to the design method in the China's code and the design method proposed in this paper respectively.Three earthquake waves and 21 test cases were adopted to perform the shaking table test.Through the comparative analysis of components damage,it was systematically demonstrated that the seismic design method proposed in this paper can realize the active control of the failure mode of the structure,effectively implement the damage design of the components,and ensure the formation of the reasonable failure mode of the structure.In the comparative analysis of the mechanical performance of the two model,it was further verified that the design method proposed in this paper can improve and strengthen the overall seismic performance of the structure,which show the effectiveness and superiority of the seismic design method proposed in this paper.