06-19-2012, 01:37 AM
On problems in the use of earthquake response spectrum methods for fluid-structure-soil interaction
Rammerstorfer, Franz G.; Scharf, Knut; Fischer, Franz D.
PVP - Vol. 157, American Society of Mechanical Engineers, New York, Sloshing and Fluid Structure Vibration -- 1989, presented at The 1989 ASME Pressure Vessels and Piping Conference, Honolulu, Hawaii, July 23-27, 1989, 1989, pdf (540/A75/1989/v.157)
The response spectrum method is well established in linear structural mechanics for estimating the maximum stresses or displacements in structures during an earthquake, characterized by the response spectra. These problems require the relative displacement spectra only. However, in order to estimate the maximum dynamically activated pressure distribution in fluid-structure interaction problems using the response spectrum method acceleration spectra are employed. With respect to a proper superposition of the individual contributions to the dynamically activated maximum pressure response, the absolute as well as relative accelerations become important. Furthermore, a suitable superposition rule must be chosen. A further problem discussed is the simultaneous horizontal (N-S and E-W) and vertical excitation of a liquid-filled storage tank. Results show that SRSS superposition is not suitable for estimating the maximum pressure or the most dangerous situations with respect to stability of the structure. Principally, from the theoretical point of view, the response spectrum method must not be used if nonlinearities are involved. A proposal for an engineering approach using the response spectrum method even for uplifting tanks is discussed. This proposal accounts for the amplitude dependence of the natural frequencies of the interaction vibrations.
PDF 1.03 MB | RAR 0.89 MB
Rammerstorfer, Franz G.; Scharf, Knut; Fischer, Franz D.
PVP - Vol. 157, American Society of Mechanical Engineers, New York, Sloshing and Fluid Structure Vibration -- 1989, presented at The 1989 ASME Pressure Vessels and Piping Conference, Honolulu, Hawaii, July 23-27, 1989, 1989, pdf (540/A75/1989/v.157)
The response spectrum method is well established in linear structural mechanics for estimating the maximum stresses or displacements in structures during an earthquake, characterized by the response spectra. These problems require the relative displacement spectra only. However, in order to estimate the maximum dynamically activated pressure distribution in fluid-structure interaction problems using the response spectrum method acceleration spectra are employed. With respect to a proper superposition of the individual contributions to the dynamically activated maximum pressure response, the absolute as well as relative accelerations become important. Furthermore, a suitable superposition rule must be chosen. A further problem discussed is the simultaneous horizontal (N-S and E-W) and vertical excitation of a liquid-filled storage tank. Results show that SRSS superposition is not suitable for estimating the maximum pressure or the most dangerous situations with respect to stability of the structure. Principally, from the theoretical point of view, the response spectrum method must not be used if nonlinearities are involved. A proposal for an engineering approach using the response spectrum method even for uplifting tanks is discussed. This proposal accounts for the amplitude dependence of the natural frequencies of the interaction vibrations.
PDF 1.03 MB | RAR 0.89 MB
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