Research On The Lead Rubber Bearing Isolation System Based On The Nonlinear Energy Response Spectra

The income energy of base-isolation buildings is absorbed mainly by the isolation layer. In order to ensure their safety and make full use of isolation system, we have to predict response of the isolation layer quickly and accurately. This thesis simulates the isolation system with Bouc-Wen nonlinear modal, studies on energy response spectrum based on Bouc-Wen nonlinear modal and establishes an applicable method to analyze rubber isolation system by nonlinear energy spectrum. We do the following research:1) We simulate the isolation system with Bouc-Wen nonlinear modal, establish single degree of freedom isolation system, derivate the formula of energy-time curve and energy response spectrum with Runger-Kutta method and compile Matlab program for time history analysis and energy response spectrum.2) With20series earthquake records selected, we establish hysteresis energy response spectrum EY(T), damping energy response spectrum ED(T), income energy response spectrum EI(T) and ductility demand spectrum μ’(T) for T=1s～6s isolated buildings occurred with rare earthquake in class II venue, the3rd group design earthquake grouping, and with the basic design earthquake acceleration of0.30g.3) We try to find the relationship from energy index EY/EI, to displacement index μ’=μ’(EY/EI) for the lead rubber bearing base isolation system and set up corresponding database.4) According to our seismic code, we put forward a predicting and checking method for isolation structures.5) Taking a7story lead rubber bearing isolated structure as our example, we carry on multi-degree of freedom nonlinear time history analysis. The result of time history analysis is compared with energy response spectrum method. The reliability of energy response spectrum and the method based on it are justified.