BUCKLING ANALYSIS OF A COOLING-TOWER SHELL WITH MEASURED AND THEORETICALLY-MODELED IMPERFECTIONS

Geometrical imperfections were measured using photogr ammetric techniq ues on an existing reinforced concrete cooling tower shell. The imperf ections, related to the radii of such a real shell, were used as input data to create a veal shape of the cooling tower. Numerical analysis was carried out for three models: (P) perfect shell of revolution, (M) shell with measured imperfections, (T) shell with a theoretical imper fection corresponding to the primary buckling mode under dead load. Th e buckling analysis was related to the linearized eigenvalue problem o f elastic shells. The shell midsurface was appl oximated by eight-node quadrilateral isoparametric finite elements. Computations were carrie d out using the ANKA computer code. Critical values of the load parame ter enable confirmation of a partial correlation between existing impe rfections and buckling modes under dead load. The most disadvantageous direction of the wind load application on the real shell was found, i n order to evaluate the decrease in the load-carrying capacity of the cooling tower shell against buckling. Theoretically modelled imperfect ions give rather unrealistic values of buckling loads of the real shel l.