Design wind loads for open-topped storage tanks in various arrangements

The present article proposes a model of wind force coefficient for designing open-topped storage tanks in various arrangements; main focus is on oil storage tanks. In our previous paper, we discussed the design wind force coefficients for isolated tanks, based on wind tunnel experiments of wind pressure distributions and buckling as well as on a finite element analysis of buckling under static wind loading. In practice, however, more than two tanks are constructed in various arrangements in a site. In such cases, the wind force distribution and the resultant buckling behavior of tanks may be affected by the arrangement significantly. Therefore, the present article focuses on the grouping effect on the wind force distribution and the buckling behavior. First, the wind pressures are measured simultaneously at many points both on the external and internal surfaces of a rigid model for various arrangements of two to four tanks in a turbulent boundary layer. The effects of arrangement pattern and gap spacing of tanks on the pressure distributions are discussed. Then, the buckling of tanks under static wind loading for various arrangements is analyzed by using a non-linear finite element method. The results indicate that the distribution of positive wind force coefficient in the windward area affects the buckling behavior significantly. Finally, based on the results obtained, we propose a model of wind force coefficient on tanks in various arrangements by modifying the model for isolated tanks that we proposed in our previous paper. For evaluating the design wind loads a gust effect factor approach is employed. The wind load evaluation is based on the quasi-steady principle and therefore the resonant effect is not taken into account.