STUDY ON GLOBAL AEROSTATIC STABILITY OF HYPERBOLOIDAL COOLING TOWERS BASED ON THE WIND TUNNEL TESTS

The researches were initiated for the global aerostatic stability of hyperboloidal cooling towers. Background experimental tests of the specifications in current codes were introduced and discussed, including the tests methods, results and comparison between tests and numerical calculations. Followed by the analysis of dynamic properties, the global aerostatic stability of a representative super cooling tower was studied based on the bifurcation buckling and limit point buckling theories, especially the effects of inner pressure and stiffening rings. The mode shapes of cooling tower shell can be deemed as the coupling of mode shapes of horizontal rings supported elastically at top and bottom edges and meridian cantilever beams supported elastically in right and left sides. For super cooling towers under static wind load, the geometric nonlinearity behavior is negligible, the transform from stability to instability is abrupt and the limit point buckling deformation is characterized by both the static deformation and bifurcation buckling mode shapes. The global stability of cooling tower decrease remarkably with the inner pressure increase; additional stiffening rings which reinforce and coordinate the shell stiffness have great favorable value for the global stability of super cooling tower and the additional stiffening ring will provide the most benefit if it locates where the most prominent buckling deformation shows up.