Influence of stiffening rings on imperfection sensitivity of hyperboloid steel cooling towers

Abstract

Stiffening rings are necessary strengthening measures for steel cooling towers. Research on the imperfection sensitivity of steel cooling towers considering different layout schemes of stiffening rings is lacking. In this study, finite element models of 160-m-high hyperboloid single-layer reticulated-shell steel cooling towers were established. A nonlinear buckling analysis of the cooling towers was performed considering different imperfection patterns and magnitudes. Simultaneously, a combined imperfection pattern that combines the lowest buckling mode shapes in all areas of the tower shell was proposed. The results showed that the imperfection sensitivity of the steel cooling tower is low and decreases with the increasing number of stiffening rings. The combined imperfection pattern is more unfavourable than the imperfection pattern of a specific buckling mode shape and is suitable for different layout schemes of stiffening rings. And the antisymmetric imperfection pattern is more unfavourable than the symmetric imperfection pattern. Additionally, the buckling resistance of a steel cooling tower decreases with the increasing imperfection magnitude, and the imperfection magnitude of Hout/300 can reasonably describe the adverse effects of imperfections on the structure. It is recommended that the combined antisymmetric imperfection pattern and the imperfection magnitude of Hout/300 are adopted for hyperboloid steel cooling towers.