SEISMIC ANALYSIS OF HYPERBOLIC COOLING TOWERS

Abstract

Hyperbolic cooling towers are shell structures with large base dimension. These structures are aesthetically pleasing, make efficient use of construction materials and can economically meet design criteria. However, a number of serious failures of shell structures during the last century has led to significant research into their behavior but further research is still required with respect to shell dynamics. The effects of the various parameters which can be used to characterize a hyperbolic cooling tower on the free vibration and the seismic response has been examined. The parametric variation was conducted on both 3D solid idealization and stick models to bring out the effects of the modeling on the outcome.The results indicate that the local buckling modes precede the conventional bending/shear bending modes. The overall contribution of local modes to the seismic response is not significant. The most dominant parameter which affects the both the dynamic characteristics and response is the height of the tower. Finally it is concluded that restrictive modeling by stick models and axisymmetric models is inadequate to establish the spatial behavior and characteristics of the cooling tower.