Numerical evaluation on shell buckling of empty thin-walled steel tanks under wind load according to current American and European design codes

Abstract

Liquid storage steel tanks are vertical above-ground cylindrical shells and as typical thin-walled structures, they are very sensitive to buckling under wind load, especially when they are empty or at low liquid level. Previous studies revealed discrepancies in buckling resistance of empty tanks between the design method proposed by the American Standard API 650 and the analytical formulas recommended by the European Standard EN1993-1-6 and EN1993-4-2. This study presents a comparison between the provisions of current design codes by performing all types of numerical buckling analyses recommended by Eurocodes (i.e. LBA-linear elastic bifurcation analysis, GNAgeometrically nonlinear elastic analysis of the perfect tank and GNIA-geometrically nonlinear elastic analysis of the imperfect tank). Such analyses are performed in order to evaluate the buckling resistance of two existing thin-walled steel tanks, with large diameters and variable wall thickness. In addition, a discussion is unfolded about the differences between computational and analytical methods and the conservatism that the latter method imposes. A sensitivity study on the geometric imperfections and the boundary conditions is also conducted. Investigation on the boundary conditions at the foot of the tank highlights the sensitivity to the fixation of the vertical translational degree of freedom. Further, it is indicated that the imperfection magnitude recommended by the EN1993-1-6 is extremely unfavorable when applied to large diameter tanks. Comments and conclusions achieved could be helpful in order to evaluate the safety of the current design codes and shed more light towards the most accurate one.

Assessment and retrofitting of an existing steel structure subjected to wind-induced failure analysis

“…(3) Where uu is the studied wind direction y. Obtaining the response of the damaged vertical bracing to the 10 min wind time-history analysis, the buckling capacity was estimated in a more precise manner via a detailed finite element (FE) simulation, according to modelling techniques presented in the literature [22].…”

The effects of extreme winds on atmospheric storage tanks

“…Maraveas et al [21] have recently presented a model to estimate the wind pressure p on the circumference of a tank, following the classical equation:…”

Strengthening effects of spiral stairway on the buckling behavior of metal tanks under wind and vacuum pressures

“…Factor k c takes the form. The space variation of pressures in the cylindrical part of the tank was assumed to be constant in elevation and variable around the circumference, as in other research works in the field [7,20]. The pressure distribution pattern on the conical roof was considered in accordance with AS-NZS 1170-2 (Appendix C5.2.2).…”

“…In all the models, the tank was assumed empty, this is worst case for tanks subjected to wind and uniform external pressure [6,18,20].…”