The Random Vibration Analysis Of Seismic Response Of Energy Dissipation Frame Structure With Viscoelastic Dampers

Viscoelastic damper,a damping device with good passive energy dissipation,is widely used in aviation,machinery and civil engineering due to its advantages of strong energy consumption,stable performance and easy installation.At present,time domain analysis method and random vibration analysis method are mainly used for dynamic analysis of viscoelastic damping energy dissipation frame structure.The linear and nonlinear analysis can be performed by time domain analysis method through the recorded or artificially generated acceleration seismic waves on the structure.Considering the randomness of the earthquake,many scholars use random vibration theory to perform random analysis on the structure.In the early stage of the project,a time domain analysis of the seismic response of the frame structure with viscoelastic dampers was conducted by the research team,and obtained the value range of the relaxation time coefficient of the viscoelastic damper,the practical formula for the economic optimization of the damping coefficient,and the calculation formula for the equivalent damping ratio.On the basis of the conclusions,random vibration theory is used to supplement its conclusions,from which the reliability of the time domain analysis conclusions will be verified,and practical calculation formulas for the seismic action of structures under random vibration will be given.The main research contents are as follows:(1)The different ground motion models and their parameter values ? ? are introduced,and the random excitation vibration equations for the frame structures with viscoelastic dampers are given.The frequency domain method is used to solve the above vibration equations.On the basis of numerical analysis,the responses such as the mean square deviation of the story displacement of each floor,the mean square deviation of the interlayer displacement,and the mean square deviation of the interlayer drift angle are studied under the random excitation of three different sites.(2)Based on the above-mentioned analysis method,the mean square deviation of story displacement,interlayer displacement and interlayer drift angle and other responses of structures with viscoelastic dampers in three types of sites are analyzed according to the economic arrangement of viscoelastic dampers in the structure,which is obtained by domain analysis conclusions.(3)Deriving the stochastic vibration equations of frame structure with viscoelastic dampers before and after equivalent damping,from which the first-order vibration mode regular coordinates of the frame structure with viscoelastic dampers installed uniformly and economically can be researched under the earthquake excitation of three types of sites.Based on this,the equivalent damping ratio curves of frame structure installing viscoelastic dampers are fitted,and the fitting formula is given.The results show that the proposed equivalent damping ratio can meet the goal of equivalent damping.(4)Based on studying the random excitation response of the frame structure installing viscoelastic dampers with braces,the influence of the damper brace coefficient and the relaxation time coefficient on the structure are analyzed,from which the mean square deviation of the seismic action of the damping structure is obtained.The results show that the brace coefficient ψ of the damper should be determined reasonably according to the relaxation time coefficient η.As long as the brace coefficient ψ is sufficiently large,the impact of the viscoelastic damper brace on the damping performance can be ignored,and the relaxation time coefficient η should not be too large.