Comparison of the behavior of isolated structures mounted on different types of friction isolators subjected to near-field earthquakes

In this study, seismic behavior of isolated structures supported on different types of friction pendulum bearings namely SFP, DCFP and TCFP subjected to seven records of near fault ground motion have been compared. To investigate the results of different isolators, they are designed in a way to have the same effective period and effective damping as two important parameters. Three-dimensional linear models of three, six and nine story steel moment frames supported on nonlinear FPS, DCFP and TCFP isolators are constructed in the SAP2000 software. By performing nonlinear dynamic analysis and investigating various structural responses such as maximum acceleration of the roof, isolators displacement, base shear and drift of the superstructure, it is showed that the isolation with the TCFP bearing are more efficient than isolation with DCFP and FPS ones. The main reason of this good behavior is five-regime backbone curve of this isolator in which the two last stages of the motion have hardening behavior. In addition, the comparison of the performance of the different isolators suggests the superiority of the TCFP bearing in controlling the displacement of the isolator, acceleration of the roof, and drift of the superstructure. The advantages of TCFP isolator are observed in all the studied superstructures with three, six and nine stories.