SEISMIC PERFORMANCE OF MULTI-STORY STRUCTURES EQUIPPED WITH UPLIFT RESTRAINED OPRCB ISOLATORS

Orthogonal Pairs of Rollers on Concave Beds (OPRCB) isolators are a recently introduced seismic isolating system which in their original form are weak against uplift. In this study, the use of Uplift- Restrained OPRCB (UR-OPRCB) isolators for seismic response reduction of multi story buildings is presented, in which three regular square plan buildings with 3, 6 and 9 stories, all having nine columns in their plan were considered. In this way the tendency of building to rocking motion and the resulting compressional and tensile axial forces in the building column, leading to additional compressive force between roller and their beds or uplift of isolator plates can be taken into account. A series of time history analysis have been conducted for each of the considered buildings. Results show that using UR-OPRCB isolators can reduce the maximum story drift values around 20%, and the maximum absolute acceleration values around 60% in average. In case of some earthquake records slight increase in the maximum story drift values is observed which can be due to the relatively high energy of those earthquakes in the range of long periods.