A Study of Ground Motion Scaling Methods for Structural Response History Analysis
Date Issued
2008
Date
2008
Author(s)
Chan, Ya-Ran
Abstract
Non-linear dynamic time-history analyses conducted as part of a performance-based seismic design approach often require that the ground motion records be scaled to a specified level of seismic intensity. Recent research has demonstrated that certain ground motion scaling methods can introduce a large scatter in the estimated seismic demands. The resulting seismic demands may be biased, leading to designs with significant uncertainty and unknown margins of safety. For high-rise buildings, high-mode effects can be rather pronounced. If a ground acceleration record is scaled without properly incorporating the design spectral accelerations at the significant periods of a building, it could seriously overestimate or underestimate the seismic demands. This study proposes a multi-mode ground motion scaling (MMS) method. This method takes into account the structural modal characteristics and aims to minimize the difference between the spectral responses of a given ground motion and the smoothed design response spectrum at the first few modes. In this research, various ground motion scaling methods are investigated using a set of nine model buildings─ referred to as the SAC buildings, each subjected to 20 specific ground motions. This study compares the effectiveness of the MMS method with the ground motion scaling procedures prescribed by current seismic codes or Sa(T) method proposed by Shome and Cornell in 1998. It is illustrated that the MMS method is effective in reducing the scatter in peak seismic demands computed from both the response spectrum analysis (RSA) and nonlinear response history analysis (NLRHA) procedures. It is demonstrated that historical ground acceleration records can be conveniently scaled with only a few more vibration modes considered for high-rise buildings. It is found that the MMS method is effective in minimizing the scatter in peak seismic demand estimates for tall buidlings. In addition, the effects of different scaling methods for a new confidence-based demand and resistance factor seismic evaluation procedure are investigated, respectively. Again, it is found that the MMS method could reduce the scatter of seismic demands and make the evaluation more effective.
Subjects
Multi-mode effects
performance-based seismic design
non-linear dynamic analysis
response spectrum analysis
scaling of ground motions
confidence-based seismic evaluation
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-97-R95521215-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):01d74d7fb64bc6ad72d85d9156fa0d44