Dynamic characteristics of combined conical-cylindrical shells

The truncated conical shape having a superimposed top cylindrical cap is widely used as a containment vessel for elevated water tanks. The evaluation of the wind and seismic responses of these tanks requires the knowledge of the dynamic characteristics of the vessels. This study reports the results of the first experimental and numerical investigation conducted to assess the dynamic behaviour of combined conical vessels. Shake table testing is conducted on a small-scale combined conical shell model. The tested specimen is then simulated numerically in a three-dimensional finite element analysis. The numerical model is validated through comparison with experimental results. An extensive parametric study is then conducted using the validated numerical model in order to determine the dynamic characteristics of full-scale combined conical vessels. Equations and charts describing the natural frequencies, the mode shapes and the generalized and effective masses of the vessels are obtained from this parametric study.