پیمان نرج آبادی فام

Effects of inherent characteristics of both isolation system (IS) and superstructure on seismic performances of aseismically base-isolated buildings subjected to near- and far-field ground motions are investigated through extensive numerical analyses. ISs considered are friction pendulum system (FPS) and high-damping laminated rubber bearing (HRB), as the most practi- cal ISs. Superstructures are 3-, 7-, and 11-story buildings with steel and reinforced concrete moment-resisting and braced frames. Seven isolation strategies are practically designed by the ISs, using three target displacements and two coefficients of friction. Eighty-four structural models are created for the 12 superstructures isolated by the two ISs. 1176 nonlinear time history analyses are carried out on the two-dimensional models of the isolated buildings subjected to seven near-field and seven far-field ground motions. Base shears, story displacements, and story accelerations are studied as the performance criteria. It is shown that the effectiveness of aseismic base isolation depends significantly on inherent mass, stiffness, and damping of the structure. The effect of isolation damping is more than mass and stiffness of the superstructure. The effec- tiveness of aseismic base isolation with the design strategies controlled by target displacement increases by increase in the inherent mass and stiffness of the superstructure, while facing reduction due to inherent increase in the isolation damping. The effects are similar in near- and far-field ground motions. Seismic performances of FPS are less sensitive to the effects of inherent structural characteristics. With the conditions and parameters set in this study, it is found that FPS performs better than HRB, specifically in near-field excitations.