Mahmood HOSSEINI - Associate Professor, Structural Engineering Research Center, the International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran
Sadegh MAHMOUDKHANI - Adjunct Lecturer, Islamic Azad University, Tehran, Iran

Orthogonal Pairs of Rollers on Concave Beds (OPRCB) isolator is a recently introduced seismic isolating system which in their original form is weak against uplift. In this study a type of U-shape restraining system is proposed for making the OPRCB isolators resistant against uplift. At first the geometrical features of the restrainer system, which has been obtained by nonlinear regression analysis, is explained and then it mechanical resistance against the uplift forces is examined by finite element analysis. Numerical results show that the proposed restraining system can tolerate uplift forces up to 8.4 tonf in elastic range within a maximum deformation of 1 mm. This amount of uplift force is a reasonable value for 5-story buildings equipped with OPRCB isolators.

U-Shape Uplift Restrainers, Finite Element Analyses, Nonlinear Regression Analysis, OPRCB Isolator, Uplift Forces