Linear and nonlinear seismic response of a 52-storey steel frame building

This paper presents the results of a study on the seismic behaviour of a we ll-instrumented 52-storey steel frame building in Los Angeles, California. This building has been subjected to ground motions from several earthquakes among which the records obtained during the 1991 Sierra Madre earthquake a nd the 1994 Northridge earthquake were selected for this study. Detailed ti me and frequency domain analyses of the recorded motions from these two ear thquakes were conducted to determine the dynamic characteristics of the str ucture. This information was used to calibrate a three dimensional dynamic computer model of the building. Nonlinear dynamic computer analyses were th en employed to investigate the response of the structure during severe grou nd shaking. The results of this study showed that by performing a linear th ree-dimensional analysis, the response of the building during past earthqua kes can be reproduced with confidence. The results also show that because o f the torsional response of this high-rise building is not negligible, two- dimensional analysis is Hot feasible for reliably predicting its nonlinear response during earthquakes. By further performing a nonlinear three-dimens ional analysis, the state and sequence of damage could also be predicted. T he study also included an investigation of the effectiveness of pushover an alysis for predicting the nonlinear behaviour of the building. This type of analysis has the deficiency of excluding the participation of higher modes , which is obvious for high-rise buildings, especially for shaking from nea r-field type ground motions. Improvements to the pushover analysis for such a type of shaking were explored. Copyright (C) 2000 John Wiley & Sons, Ltd .