Research Of Improved Measures For Seismic Design Category Ⅱ Considering R-μ Principle And Other Integrated Influence

The R -μrelations have been accepted by foreign design codes widely. The R -μrelations are that the correlations between adopted smaller earthqake action level and structures ductility demand in whichever intensity region are same. But the Chinese seismic design code is the only code which dose not accept the R -μrelations. It takes different seismic measures and choses the same earthquake design level in all intensity regions respectively.For investigating which one is more reasonable, the follow research work is finished preliminarily in this thesis.①Considering that several stiffness models are adopted in inelastic dynamic response analysis of reinforced concrete constructures, the paper has analysed and valued the characteristic of stiffness models respectively, after pointing out the deficiencies of some stiffness models, and then adpoted the Fardis stiffness model which is based upon the large numbers of tests, also has contrasted to the result of inelastic dynamic response analysis of multi-story and multi-bay reinforced concrete frame. Then the paper proves that different stiffness models can influence the result of inelastic dynamic response analysis.②On the condition that the seismic measures of Chinese Intensity Region 9 with seismic design categoryⅠis similar with that of Eurocodes high ductility, the paper has designed one typical frame of Chinese Intensity Region 9 with seismic design categoryⅠand two typical frames of European Intensity Region 0.4g with high and middle ductility, and then has contrasted their performance of inelastic dynamic response analysis under the major earthquakes in Chinese 0.4g zonation. The result indicates that the Chinese design earthqake action level is closer to that of European high ductility; the the dynamic response character of Chinese sample is similar to that of European high ductility sample.Then we can be sure that the performance of frames designed according to the measures of Chinese Intensity Region 9 with seismic design categoryⅠand Eurocodes high ductility can be contrasted.③In order to obtain seismic behavior of Intensity Region 9 with seismic design categoryⅠ, three series of sample to adjust the seismic mearures of Chinese Intensity Region 8 with seismic design categoryⅡ. The three schemes are : (1) adjust theηcof∑M_c=η_cM_b; (2) adjust the 1.2 of∑M_c= 1.2Mbua; (3) adjust the force reduction factor R, namely 2.86. Then typical frames have been designed according to every adjusted schemes and finsihed inelastic dynamic response analysis, investigated whose sesmic performace is similar to that of Intensity Region 9 with seismic design categoryⅠ.Through analysis we can conclude that for Intensity Region 8(0.3g), the seismic mearures which are weaker than that in Intensity Region 9 can obtain seismic behavior of Intensity Region 9,and we have discussd academic bases of this conclusion.According to the analysis above we can conclude tendentiously that middle course which is inclined to foreign method maybe more suitable, considering Chinese gradually weaker measures with the decrease of Intensity Region and foreign method that conform to the R -μrelations strictly. Because there are more non-seismic details and other advantaged measures which may benefit the frames response more and more as the Intensity Region decreases, the demand ofμcan be relaxed when R is same. Of course, this conclusion will be affirmed after contrast ananlysis of Intensity Region 8(0.2g),7(0.15g) and 7(0.1g) has been finished.