| Abstrakt: |
Purpose: An extensive study is made of the seismic behaviour of frames isolated by FPS (friction pendulum system) subjected to a sequence of the mainshock and four aftershocks. The mainshock and aftershocks are real, taken from PEER Berkeley database. The performance of the frame is assessed with the help of the maximum and residual responses in each phase of the episodes. Methods: A nonlinear time history analysis (NLTHA) is carried out in SAP 2000 to find the responses. The study takes into account various earthquake types, including far-field and near-field earthquakes. For the near-field earthquake, both near field with forward directivity effect and near field with fling step effects are considered. Further, the friction property of the FPS is varied to study its impact on the seismic response of the frame. Base shear, number of hinges, top floor displacement, top absolute acceleration, and isolator displacement are some of the response parameters of interest. A ten-storey building frame is analysed using SAP 2000. Results: The present study examines the effects of a sequence of far-field (FF) and near-field (NF) earthquakes on a 10-storey frame which was isolated by the FPS. The seismic responses include base shear (BS), isolator displacement (ISD), number of plastic hinges (NP), top absolute acceleration (TAC), top-storey displacement (TD), and maximum inter-storey drift (MIDR). The residual TD, ISD, and MIDR are found to vary with the number of aftershocks differently for FF, NFD, and NFF earthquakes and different combinations of friction coefficients. Conclusion: The important conclusions of the study include (i) the friction properties of the isolator have a substantial effect on the maximum and residual responses for each episode; (ii) the base shear, number of plastic hinges, and top-storey absolute acceleration remain almost insensitive to the number of aftershocks; and (iii) better restoring capability of the FPS system is exhibited in aftershocks. [ABSTRACT FROM AUTHOR] |
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