Tank shell stability: refined design schemes

Structural mechanics

In many ways, the reliability of vertical cylindrical tanks is determined by the resistance to buckling of the wall. In the current work, a variant of a detailed design scheme is considered, taking into account the presence of a spiral technological staircase for servicing the tank roof. The possibility of using the specified structural element as an external reinforcement to increase stability is analyzed. Finite element models of tanks with volumes of 10..30 thousand m3 were developed. The models took into account the actual distribution of the wind flow for tanks with a circular staircase. Using a multifactorial experiment, an analysis of the stability and stress state of the tank wall was carried out. The variable parameters were: the design solution of the stairs, the dimensions of the tanks and the load. Corresponding graphs and diagrams were constructed. As a result, the design solution and the recommended angle of inclination of the spiral staircase in the range of 30–40° were substantiated. The application of the obtained solutions improved the stability in the annular direction by up to 13 % compared to standard solutions. Wall displacements from wind load are reduced by 14 %, in turn, local stresses in the ladder attachment areas increased by no more than 5 %. In general, the inclusion of spiral staircases significantly increases the stability of the tank wall and can be considered as a good alternative to standard reinforcement methods.