Seismic performance of steel moment frames with variable friction pendulum systems under real ground motions

Abstract

Many researchers have already acknowledged that the base isolation system as the most feasible and economical method for civil engineering structures exposed to the seismic excitation. The Friction Pendulum Systems (FPS) have steel concave surface connected with articulated friction slider and utilized the concept of pendulum for lengthening the period of the superstructure so as to dissipate the seismic energy. The present study investigates on various design approaches for the evaluation of the seismic response of steel frames equipped with FPS. The response of isolated frames is simply adjusted by several parameters such as the friction coefficient (μ), the radius of curvature (R), the isolation period (T) and the axial load and so 2D, three bay 3 and 7-storey steel moment resisting frames (SMRF) are designated as isolated frames in order to examine the effect of variation of the R and the friction coefficient on the seismic response of the isolated frames. The R and μ are predefined as 1, 1.55, 2.25 and 0.025, 0.05, 0.1, respectively. The seismic response of the modelled isolation systems has been evaluated through nonlinear time history analyses, a set of ground motions using SAP2000 software. The local and global deformations are employed to compare the seismic performance of different isolation frames through nonlinear analysis. The results showed that the isolated frames having greatest radius of curvature with lowest friction coefficient exhibited better seismic performance than other models in terms of the local and global deformations.