Free and random vibrations of column-supported cooling towers

A transfer matrix formulation is used to develop an efficient algorithm to analyze the dynamic behavior of a cooling-tower structure, which consists of a thin hyperbolic shell of revolution supported at the base by flexible columns. The paper is divided into three parts: (1) free vibration, (2) seismic excitation, and (3) wind excitation. The seismic effect is assumed to be dominated by the horizontal ground acceleration, modeled as an evolutionary random process. The wind pressure field is separated into a static part and a fluctuation part, the latter being modeled as a statistically stationary random field. Numerical examples are given to illustrate the application of the theory. In the case of wind excitation, surprising results are found that the fluctuation part of the structural response is not always dominated by the lowest frequency modes, contrary to common expectations.