Inelastic stability of conical tanks

Stability of combined imperfect conical tanks under hydrostatic loading

“…Following the collapse of the Fredericton conical tank in the early nineties, an extensive research program focusing on the stability of such structures was initiated in Canada. The buckling behaviour of conical tanks, including the effect of geometric imperfections and residual stresses, was studied by El Damatty et al [6,7]. A simplified design procedure was then developed by El Damatty et al [8], followed by another investigation that was conducted by El Damatty and Marroquin [9], where a design approach was developed to ensure safety of hydrostatically loaded combined steel conical tanks against buckling.…”

Simplified procedure for design of liquid-storage combined conical tanks

“…Geometric imperfections have a significant impact on the stability of thin shell structures. El Damatty et al [7,8] have shown that an imperfection pattern having an axisymmetric distribution along the tank perimeter and varying along the shell generator as a sine wave results in the lowest limit load for hydrostatically loaded conical shells. The assumed sine wave is assigned a wavelength equal to the buckling wavelength of its perfect counterpart [6].…”

“…In the current study, the aforementioned design procedure is extended to include combined conical tanks taking into account the variation of both the angle of inclination of the conical part of the vessel as well as the yield strength of steel. The study is carried out numerically using the non-linear consistent shell element that was developed by El Damatty et al [7] and validated by El Damatty et al [7,8] using the experimental results of Vandepitte et al [6]. An extensive parametric study is conducted to assess the buckling capacity of wide spectrum of geometric parameters of combined tanks that cover the range of practical dimensions.…”

Imperfection sensitivity and stability of an elastic-plastic conical shell under axisymmetrical load

“…An inverse has to be made to the first set of three relations in (11) in order to substitute the strain tensor components into the compatibility equation (5). The respective coefficients of the resulting set of equations are of the following form:…”

“…By extending the analysis to include nonlinear material behaviour, it was found that for conical tanks of practical dimensions, yielding precedes the elastic buckling and that thus inelastic buckling governs the failure of these structures. The aim of another work, [5], was to study the effect of different imperfection shapes on the inelastic stability of liquid-filled conical tanks and to determine the critical imperfection shape that would lead to the minimum inelastic limit load. The study was carried out numerically, using a self-developed shell element and applied to simulate a number of conical tanks with imperfection shapes in the form of Fourier series of equal coefficients.…”