Linear and Nonlinear Analysis of a High-rise Building Excited by Earthquake: Lineær og ikke-lineær analyse av høyhus utsatt for jordskjelveksitasjon

Abstract

The purpose of this thesis is to evaluate the linear and nonlinear response of a high-rise building located in Norway. The Oslo Plaza building, located in Oslo, has been chosen for this purpose. A finite element model of the structure was created in the structural analysis program SAP2000 with emphasis on representing the nonlinear behavior as correctly as possible. Modifications of ground motion data was performed to betterrepresent a typical earthquake in a Norwegian environment, and the seismic response ofthe building was investigated using several different analysis methods.Oslo Plaza was found to behave linearly for earthquakes with an expected return periodof 475 years, while for a 3000-year earthquake major nonlinear effects are expected tooccur especially in the longitudinal direction. Oslo Plaza should however still not collapse during an earthquake of this size, even though it is expected to experience permanent deformations.While dimensioning high-rise buildings for 475-year earthquakes the response spectrummethod described in EC8 was found to be adequate. For most engineering firms this isby far be the easiest method for analysing a high-rise building considering its simplicity and the fact that nonlinear direct integration time history analyses require significantly more computational power and calculation times.An interesting point found during the work with this thesis is that the swimming poollocated in the top-stories of Oslo Plaza might work as a tuned liquid damper during thebuilding s linear seismic response. This damping effect was found to have the potentialto be significant if the dimensions of the swimming pool had been altered by only a fewmeters.Keywords: Ground-motion; High-rise structure; Oslo; Nonlinear; Tuned liquid damper;Dynamic analysis