ABSTRACT A vibration isolation system using spring units and visco ...

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4.4 Results The acceleration time histories of X and Y directions for the roof floor resulting from the three dimensional frequency response analysis and the three dimensional time history response analysis based on the EW wave of El Centro in X direction are shown in Fig. 13. Both time histories are very similar in wave form and maximum acceleration. (a) Frequency response analysis (b) Time history response analysis Fig. 13 Acceleration response (RFX,Y-direction) (a) Frequency response analysis (b) Time history response analysis Table 3 Maximum response Fig. 14 Transfer function (RF X-direction) The transfer functions of the two response analyses are shown in Fig. 14. Both are very similar below 10 Hz, but above 10 Hz the response of the time history analysis is lower than that of the frequency response analysis. The detailed analysis results are shown in Table 3.
5. SHAKING TABLE TEST OF THE ISOLATED BUILDING MODEL 5.1 Shaking table test 5.1.1 Model The model was designed to have the same natural frequency and the same damping ratio as the real building. The isolation system was composed of six springs and four dampers. The accelerations at the top and bottom of the frame, and the relative displacement between the bottom of the frame and the top of the shaking table were measured. Fig. 15 shows the model and measurement points. 5.1.2 Loading (1) Sinusoidal sweep excitation The model was shaken by a sinusoidal sweep wave in the direction of the longer side (X), the shorter side (Y) and the vertical direction (Z). The acceleration was 20 gal and the range of frequency was 0.3 Hz - 10.0 Hz. (2) Seismic excitation Taft wave, El Centro wave and Hachinohe wave were used for the input of the shaking table. For each seismic wave the model was shaken in Y direction only, Y and Z directions combined and all three directions. 5.2 Analytical method The analytical method of the shaking table test was the same as the one explained already above. The analysis model is shown in Fig. 16. The upper structure was assumed to be a shear beam element. The weight of the model was concentrated in two separate masses at the top and the bottom. The material properties of the analysis model were based on the results of a random noise test without the isolation system. 4-parameter model Longitudinal cross section Lateral cross section Fig. 15 Specimen Fig. 16 Analysis model
Page 1 and 2: ABSTRACT (Revised English Version)
Page 3 and 4: 2.2 Composition of the system 2.2.1
Page 5 and 6: (3) Results Fig. 7 shows the relati
Page 7: 4.1.2 Modelling of the damper The d

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