Theoretical and experimental study on unconsolidated isolation structure

To analyze vibration reduction effect of isolation structure with unconsolidated conical bearings,energy dissipation mechanism of bearings and tension performance of bearings,the shaking table tests of a 1:4-scale model of two-floor steel frame with unconsolidated conical bearings under the input of horizontal or vertical earthquake were conducted.Seismic responses of top structure and conical bearing were analyzed by inputting earthquake wave with different magnitudes and types.Experimental results indicated that compared with table input peak acceleration,the max acceleration of isolation layers of the structure had been reduced by 10%~20%,and the max acceleration of model top structure had an increment of 10%~40% under unusual ground motions of 8 and 9 intensity.In spite of this,it had obviously vibration reduction effect compared with normal anti-seismic structure.The hysteretic curves of the bearing under different earthquake waves were full and symmetric.The upper and lower covers dissipated earthquake energy by compressing the viscoelastic material when they formed relative displacement.The energy dissipation mechanism of bearings was clear.The effects of ground motion characteristics on tension performance of bearings were obvious,but overturning and collapse of model structure didn't appear.The results of the test indicate that the unconsolidated conical bearing has good damping effect and the promoted value to lower-layer building for vibration reduction.