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Investigating the effect of different number of horizontal as well as vertical ground motions on base isolated structures with different heights

Elcik Erol, Bengü
The main goal of this study is to investigate the effects of the changes in selecting procedure of real ground motion records to be used in non-linear time history analysis on base isolated structures with friction-pendulum system. The revision involves selecting 11 ground motion records instead of 7 records and taking into account the vertical components of earthquakes instead of considering just horizontal components. Specific to this study, the main parameters employed for investigation will be base reactions, inter-storey drift ratios, peak floor accelerations, isolator displacements and axial loads on isolators. The main reason for selecting these parameters is that the inter-storey drift ratio and peak floor acceleration are the main parameters affecting structural system design, and base reactions, isolator displacements and axial loads on isolators are the main parameters affecting isolation system design. These parameters were evaluated using non-linear time history analysis method with ground motion records, which are selected and scaled using the seismicity of Isparta, on structures having 3 different numbers of floors. The analyses performed in this work indicates that increasing the number of selected ground motion records causes a decrease in all parameters evaluated. While consideration of vertical components of ground motions do not have any identifiable effect on peak floor accelerations, inter-storey drift ratios or isolator displacements, increases the variation of axial loads on isolators and base reactions. Another conclusion is that the revision on Turkish seismic code increases the execution time for analyses.