PSI - Issue 28

G.N. Gusev et al. / Procedia Structural Integrity 28 (2020) 2328–2334 Author name / Structural Integrity Procedia 00 (2019) 000–000

2330

3

Fig. 1. General view of the vertical steel oil tank.

A comparative analysis of the results obtained for different types of models was carried out using the obtained results. It is seen that equivalent stresses are distributed more equally over the walls of the structure with buckling compared to the tank of an ideal shape. Under static loading conditions, there is an insignificant excess of permissible stresses near the welded seams, whereas the rest of the surface of the tank does not experience significant, compared to limit values, stresses. Under dynamic loading, the first five load-unload cycles of the tank were considered under the assumption that the tank was initially subjected to mass forces (Dobromyslov, 2004). It has been found that already during the first loading cycles the plastic (residual) deformations of the zones with buckling reach a certain value and do not grow, and the elastic component amplitude remains unchanged. This means that, within such conceptual framework (defects are treated as a shape curvature), the cyclic loading of the tank wall does not lead to an irreversible deformation of the wall at the place where the stress exceeds the design resistance of the steel (Fig.2).

Fig. 2. Equivalent stresses distributed over the tank walls. The scale is limited to the characteristic strength of the wall material. Zones with increased stress values are shown in grey.

Qualitative and quantitative analysis of the calculated results provides evidence that the proposed model can be used to reveal the reliability margin of the examined structure, even when taking into account the observed deviations of the tank shape from the design variant. Prediction of the strain rate under varying operating conditions is valid to