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Vol. 40 (1999) No. 1 April n. 129


Dynamic response of cooling towers under harmonic excitations of their bases

< Table of Contents for Vol. 40 (1999) No. 1 April n. 129
  • Journal Name: Journal of the International Association for Shell and Spatial Structures (J. IASS)
  • ISSN: (Electronic Version) 1996-9015
  • ISSN: (Print Version) 1028-365X
  • Issue: Vol. 40 (1999) No. 1 April n. 129
  • Title: Dynamic response of cooling towers under harmonic excitations of their bases
  • Author(s): O. M. Sadiq
  • Keywords: cooling tower, dynamic, modal analysis
Abstract
The dynamic response of cooling tower shells when subjected to harmonic excitations at their bases is discussed. The governing system of dynamic equations is derived with the help of tensorial analysis, using the surface of hyperbolic paraboloid as a model. The system of dynamic equations is then solved by decomposing the displacement components into Fourier series along the circumferential and time coordinates. The dynamic response of a reinforced concrete hyperbolic cooling tower of height 150 m, base diameter 120 m and wall thickness 20 cm, when subjected to harmonic excitations at its base is taken as a demonstration problem. Results of our analysis show that at any excitation frequency of the base, the dominant contribution in the modes of vibration of the tower is the dynamic deformation component corresponding to the vibration mode with frequency of the same value as the harmonic excitation frequency of the base. The vibration modes at different excitation frequencies of the base are presented. The free vibration analysis of the tower is also carried out.

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