Comparison between fixed base and isolated base in seismic response of high-rise buildings: a case study

Özet

In this study, the influence of soil condition under the isolated and fixed bases is studied by using ETABS 16 software for a high-rise regular building. A regular buildingwith 10 floors is modeled and the results are obtained for story displacements, storyshear forces and spectral acceleration according to the Uniform Building Code 97(UBC-97) code. The time history analysis has been performed by using 1999 Izmitearthquake record. 3 types of soil which have different stiffnesses are considered inthis study. The results show that the value of the base shear increases when the soilstiffness decreases. It also noticed that the spectral acceleration is larger in soft soilcondition than that of other soil conditions; and this confirms that the structural response spectrum depends on the soil condition. In addition, when using base isolatedbuilding the drift of lower floors will be larger than that of using base isolated, but inthe upper floors the drifts of fixed base building will be larger than that of the isolatedbase building. Finally, the time history method in the seismic design will producebase shear less than that from equivalent static method, so calibration factor for design purpose shall be used.