Researches On The Effects Of Damping On Isolation System

The re-centring spherical-surfaced sliding isolation system is a kind of arc surface sliding friction system. Besides the characteristics of the general sliding friction system, it has great capacity of displacement restriction, restoration and strong stability. To ensure the structural safety, the system can isolate a structure from the ground, prolong the structural period, change the dynamic characteristics of structures, absorb and consume seismic energy by developing isolation layer.The re-centring spherical-surfaced sliding isolation system is a new isolation system independently designed by Prof. Chen Qinglai of Shandong University. The system consists of re-centring spherical-surfaced sliding isolation bearings and mild metal dampers. The paper introduces the large-scale shake table experiment taken on this isolation system and analyzes the data of EL-centro (ELC) earthquake wave concerning the effect of the bearings additional damping on isolating affection.First, the experimental data is analyzed from the point of accelerations. The paper respectively compares acceleration time histories, the maximum accelerations and the maximum average acceleration of steel frame in two directions from first story to sixth with different seismic intensity and levels of damping. The effect of isolation system is as follows: the third level of damping (inherent damping of the bearings and 12% additional damping) is superior to the second level (inherent damping of the bearings and 0% additional damping), which is better than the first level (inherent damping of the bearings and 88% additional damping).Second, the experimental data is researched from the point of energy. The paper respectively compares energy time histories, the total energy and the predominant energy of steel frame in two directions from first story to sixth with different levels of damping under the 400gal seismic intensity. The effect is as follows: the energy ratio of the X direction is 2:1:0.75 and the Y direction is 1.3:1:0.9 under the three levels of damping, which means the energy absorption capacity of the third level damping is the best, and next comes the second level.In the end, according to the results above, the conclusions are as follows: the additional damping should maintain a certain level in order to perform the best of the isolation system; the effect of additional damping is not so significant in the direction of the low stiffness compared with the high stiffness direction in the structure. At the same time, the deficiencies in the paper and future work are discussed finally.