H.A. Mang, H. Flögl, F. Trappel, H. Walter:
"Wind-Loaded Reinforced Concrete Cooling Towers: Buckling or Ultimate Load?";
Engineering Structures, 5 (1983), 3; 163 - 180.
Wind loadings govern the design of most cooling towers. Until now, proof of sufficient safety against buckling under wind load has been a major concern for the designers os such shells.In this paper it is demonstrated that a typical cooling tower made of reinforced concrete would not buckle - at least not in the classical sense of the word. Failure would rather be initiated by rapid propagation of cracks in tensile zones followed by temporary stiffening and, finally, by yielding of the reinforcement.
The theoretical part of this paper is restricted to a presentation of the constitutive model, discussionof the equation for incremental-iterative ultimate-load analysis and of the condition for instability. The numerical part contains a detailed study of a built hyperbolic cooling tower.
It is shown that: (a), buckling loads resulting from linear and geometrically nonlinear prebuckling analyses are considerably larger than the ultimate laod; and (b), results based on a certain form of 'equivalent axisymmetric pressure' are in the unsafe side of corresponding results form the 'actual' wind load. It is also demonstrated that the 'crack load', representing a lower bound to the ultimate load, can be estimated by means of a linear-elastic nonaxisymmetric analysis of the cooling tower.
Keywords: cooling tower, buckling, wind load, equivalent axisymmetric pressure, finite element analysis, layer model, smeared cracks, ultimate load
http://dx.doi.org/10.1016/0141-0296(83)90014-7