Study The Variation of Structural Demands Using Method-Dependent Spectrum Compatible Time Histories As Input Ground Excitation
Date Issued
2009
Date
2009
Author(s)
Hsu, Chih-Hung
Abstract
The goal of earthquake-resistant design is to produce a structure or facility that can withstand a certain level of shaking without excessive damage. This level of shaking is described by a design ground motion, which can be characterized by design ground motion parameters. Generally, spectrum-compatible seismic excitations are required when dynamic time-history analysis is used for determining the response of a building structure. This paper describes the simulation methods to generate the artificial ground motion time history compatible with a target acceleration response spectrum. Five different approaches to generate spectrum compatible ground motion are presented. First, a wavelet-based procedure has been used to decompose a recorded accelerogram into a desired number of time-histories with non-overlapping frequency contents, and then each of the time-histories has been suitably scaled for matching of the response spectrum of the revised accelerogram with a specified design spectrum. The key idea behind this iterative procedure is to modify a recorded accelerogram such that the temporal variations in its frequency content are retained in the synthesized accelerogram. Second, a method based on the modification of original wave form by using a series of modification functions which is in relating to a damped single-degree-of-freedom is used. Third, method from manipulate the amplitude of Fourier transform for overall matching is also discussed. Fourth, spectrum compatible ground motion using generated phase spectrum is also discussed. Finally, the multi-mode ground motion scaling (MMS) method takes into account the structural modal characteristics and aims to minimize the difference between the response spectrum of a selected ground motion and the design spectrum at the first few modes. Discussion on the overall shape, duration and frequency contents, and peak acceleration and phase contents of the artifical ground motion time history are made.inally, this report also presents results from a study on the effects of different types of spectrum-compatible excitations on the response of building with different height. A SDOF nonlinear system, a 6-story and a 12-story building are used in this study. Nonlinear time-history analyses were conducted by using the spectrum-compatible excitations (i.e., accelerograms) generated from different approach.
Subjects
spectrum-compatible
dynamic time-history analysis
artificial ground motion time history
response spectrum
wavelet transform
phase spectrum
multi-mode effect
Type
thesis
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