The vibration and stability of axially loaded sandwich cylindrical shells with the functionally graded (FG) core with and without shear stresses and rotary inertia resting Pasternak foundation are investigated. The dynamic stability is derived based on the first order shear deformation theory (FSDT) including shear stresses. The axial load and dimensionless fundamental frequency for FG sandwich shell with shear stresses and rotary inertia and resting on the Pasternak foundation. Finally, the influences of variations of FG core, elastic foundations, shear stresses and rotary inertia on the fundamental frequencies and critical axial loads are investigated
The objective of this study is to evaluate the effect of the geomembrane/geotextile interface on the seismic response of small-to-moderate height structures. Three building models with first-mode natural frequencies changing between 2–4 Hz (representing two, three and four storey structures) were tested with and without the addition of geomembrane/geotextile interface using the shaking table test setup by employing harmonic and modified/scaled ground motions. Experimental results showed that the geomembrane/geotextile interface significantly reduced the floor accelerations, especially at moderate-to-high ground shaking levels. The interaction between the first-mode natural frequency of the model and the predominant frequency of the input motion is significant, and the interface is most effective when these two frequencies are close to each other. This effect is more clearly seen when the harmonic motions are employed during the tests compared to the modified/scaled ground motions. The results of the tests with modified/scaled ground motions were used to evaluate the efficiency of the composite liner system in reducing the spectral accelerations in the frequency domain. The results presented here document that the geomembrane/geotextile interface reduces the floor accelerations in a certain frequency range and underline the potential of this interface to be used as a base isolation material.
This article is the result of an investigation on the influence of a Pasternak elastic foundation on the stability of exponentially graded (EG) cylindrical shells under hydrostatic pressure, based on the first-order shear deformation theory (FOSDT) considering the shear stresses. The shear stresses shape function is distributed parabolic manner through the shell thickness. The governing equations of EG orthotropic cylindrical shells resting on the Pasternak elastic foundation on the basis of FOSDT are derived in the framework of Donnell-type shell theory. The novelty of present work is to achieve closed-form solutions for critical hydrostatic pressures of EG orthotropic cylindrical shells resting on Pasternak elastic foundation based on FOSDT. The expressions for critical hydrostatic pressures of EG orthotropic cylindrical shells with and without an elastic foundation based on CST are obtained, in special cases. Finally, the effects of Pasternak foundation, shear stresses, orthotropy and heterogeneity on critical hydrostatic pressures, based on FOSDT are investigated.
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