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Earthquakes and Structures
  Volume 7, Number 6, December 2014, pages 1303-1316
DOI: http://dx.doi.org/10.12989/eas.2014.7.6.1303
 


Combinatorial continuous non-stationary critical excitation in M.D.O.F structures using multi-peak envelope functions
S. Hooman Ghasemi and P. Ashtari

 
Abstract
    The main objective of critical excitation methods is to reveal the worst possible response of structures. This goal is accomplished by considering the uncertainties of ground motion, which is subjected to the appropriate constraints, such as earthquake power and intensity limit. The concentration of this current study is on the theoretical optimization aspect, as is the case with the majority of conventional critical excitation methods. However, these previous studies on critical excitation lead to a discontinuous power spectral density (PSD). This paper introduces some critical excitations which contain proper continuity in frequency domain. The main idea for generating such continuous excitations stems from the combination of two continuous functions. On the other hand, in order to provide a non-stationary model, this paper attempts to present an appropriate envelope function, which unlike the previous envelope functions, can properly cover the natural earthquakes\'accelerograms based on multi-peak conditions. Finally, the proposed method is developed into the multiple-degree-of-freedom (M.D.O.F) structure
 
Key Words
    random vibrations; continuous critical excitation; envelope functions; power spectral density
 
Address
S. Hooman Ghasemi: Auburn University, USA

P. Ashtari: Civil Engineering, Zanjan University, Iran
 

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