Research On The Ratio(λ)of Components’ Elastoplastic Damage Energy In Pseudo-Elastic Plasticity Method Of Frame Structure

The peseudo-elastic plasticity method of frame structrues defines the initial stiffnessreduction factor k of the components based on the energy equivalence principle firstly, thenthe ratio(λ) of the components’ elastoplastic damage energy in the real earthquake is used toobtain the final stiffness reduction factor. The stiffness-reduced frames run the elastic timehistory analysis and the results are used to estimate the results of elastoplastic analysis, so theresult of elastoplastic analysis can be estimated by the result of elastic time history analysis.The purpose of this method is to reduce the complexity of elastoplastic analysis for thestructure under rare earthquake. In order to improve this method, the ratio λ which is veryimportant to the accuracy of analysis are studied in this paper. The recommended values of λfor the structures which have different stories and different site condition are given in thispaper. The contents are as follows:1) Ten appropriate seismic waves for each structure are selected in the new PEER groundmotion database. The search criteria are the target spectrum and site condition.2) Six reinforced concrete frame structure of different stories in site II and site III aredesigned for analysis. The elastoplastic drifts of each structure can be got by elastoplastic timehistory analysis using Perform-3D.3) Structures are divided into two parts, and different values of λ are taken consideringthe difference of the degree of plasticity. The final stiffness reduction factors are calculated forthe structures of different stories in site II. Then the elastic time history analysis results ofstiffness-reduced frames are compared with elastoplastic time history analysis results. Thebest value of λ which makes the minimum absolute error of drifts can be abtained, and theaverage error of lower stories is the first evaluation criteria,the upper part is secondary.4) Similarly, using the same story division method and evaluation criteria, the componentstiffness of reinforced concrete frame structures of different stories in site III can be reduced.Then the elastic time history analysis results of stiffness-reduced frames are compared withelastoplastic time history analysis results to get the best value of λ which makes the minimumabsolute error of drifts.5) The division method of stories and the pseudo-elastic plasticity method in differentsite conditions are both proved feasible by the research above, and the variation of the best λvalue for the reinforced concrete frame structure of different stories in different site conditionsis also obtained.