Research On Simplified Design Method And Optimization For Energy Dissipation Structures With Viscous Dampers

Earthquakes have been a serious threat to the survival and development of human beings.With the improvement of technology and people’s living standards,the ability to prevent and resist earthquakes has also been continuously improved.Energy dissipation technology is effective,safe,reliable and economical.Many engineering seismic experts and scholars at home and abroad are actively committed to develop and apply this technology.There are many design methods of energy dissipation.Among them,the displacement-based method can better consider the structural deformation and is widely used.However,shortcomings still exist,mainly in the selection of the target displacement profile,the determination of the additional damping ratio,and the determination of the damper parameters of each layer.The unreasonable choice of the above three aspects will lead to excessive iterative calculations,failure to achieve the expected shock absorption effect or uneconomical design results.This paper improves these shortcomings.The main research contents and results are listed as follows:(1)Briefly introduce and deduce the mechanical model,basic parameters and equivalent linear damping coefficient of the viscous damper.Introduce the common seismic response analysis methods for energy dissipation structures with viscous dampers.(2)First,considering the influence of higher-order mode shapes,the new method based on mode-superposition response spectrum method to calculate additional equivalent damping ratio required by the structure is proposed.Obtain the target seismic responses of the energy dissipation structure based on equivalent damping ratio.Second,based on energy theory,put forward a distribution method,in which the damping coefficient is proportional to the(α +1)-th power of the story drift.Considering the existing distribution methods: damping force is proportional to the shear force between layers,damping coefficient is evenly distributed along the floor,damping coefficient is proportional to the shear force between layers,damping coefficient is proportional to interlayer displacement,derive the expressions of the distribution ratio coefficients under different distribution methods based on the formula of strain energy method for additional damping ratio.Third,aiming at the design goal of "structure will not be damaged in the middle earthquake and can be repaired in the large earthquake",a simplified design method for energy-dissipated structures with viscous dampers is proposed.This method has clear design goals,simple calculation.(3)Based on the simplified design proposed in this paper,apply PKPM and ETABS software to reinforce a 12-layer regular frame and a 6-layer vertical stiffness irregular frame with linear viscous dampers.The results show that the seismic responses of the controlled structures are closer to the target values,the dampers of each layer can be designed in one time.The damping coefficients under different distribution methods all can meet the design goals.Among them,the method of damping coefficient being proportional to the square of story drift produces the smallest damping coefficients,which is the more economical distribution method.(4)Optimize the total additional damping coefficient of the structure with the genetic algorithm,and at the same time the total damping coefficient is distributed to each floor in a manner that the damping coefficient is proportional to the square of the story drift.Ensure the maximum story drift angle under moderate earthquakes less than the allowable value and meet economic requirements.In this paper,a new optimization model is established to optimize a 12-layer frame structure and proves the economics of the results through comparative analysis.