Non-Linear Dynamic Response of Liquid Storage Tank Excited by Strong Ground Earthquake

Abstract

This paper presents a fully coupled fluid-structure-soil interaction analysis technique for rectangular liquid-contained structures subjected to horizontal ground excitation. The hydrodynamic interaction of the contained liquid with the structure can be considered as impulsive pressure loads exerted on the wetted interface during ground excitations of earthquake waves. The intensity of the horizontal ground forces is found to be independent upon the response of the system, which is known as external excitation. The multiple time scale method is used to construct a first order uniform expansion yielding two first order non-linear ordinary differential equations governing the modulations of the amplitude and phase angle for the two resonance modes of external excitations. When the first and second mode is externally excited separately, the results show that amplitude response can reach the steady state and unsteady chaotic behavior in the same time depending upon the initial conditions and external detuning parameter σ_x . The system response of the steady state amplitude can also take multiple values according to initial conditions within a certain range of the external detuning parameter. The response of steady the amplitude behaves as stable and unstable oscillator within a certain range of σ_x as soft or hard non-linear system. The unsteady amplitude is taking the chaotic behavior of the non-linear system in different forms varying with σ_x . The results are indicating that strong non-linearities which introduced due to impact and high non-linearity can suppress the amplitude and domain of fluctuations in the two resonance modes of excitations.
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