Research On The Isolation Effect Of Combined Isolation System Composed Of Rolling Friction Bearings And Lead Rubber Bearings

Setting some kinds of isolation device between the upper structure and the foundation or one designed layer, the seismic responses of upper structure can be reduced because its natural vibration period of is extended.Presently, some isolation devices are widely used such as the lead rubber bearing (LRB), the friction sliding bearing (FSB), and the combined isolation system (CIS). The CIS is combined with LRB and FSB in different proportions, in either series or parallel way.The isolation effects of two kinds of CISs were analyzed using SAP2000 in this paper. The first kind is composed by LRBs and roller, the second kind is composed by LRBs and rolling-ball.Firstly, the seismic responses of a test model which was set with the CIS (the proportion of rubber bearings and roller is 1:1), was simulated and the isolation effect were analyzed. And then, an engineering project which were set with two kinds of isolation devices separately (one is with LRBs, another is CIS composed 20 LRBs and 7 rolling-balls), the seismic responses calculated and the isolation effect were the analyzed in this paper.The results of the research show that:1.For the CIS composed of LRBs and rollers, the isolation effect in the rolling direction of the roller is better than that in the sliding direction. Nevertheless, for the CIS composed of LRBs and rolling-balls, the isolation effect are better in both directions.2.Both LRB and CIS can absorb the seismic energy that is transmitted to the upper structure,and the seismic responses of the upper structure can be reduced.3.With the same number and positions of the bearings, the isolation effect of a structure using CIS is better than that using LRBs only.