Experimental identification of the vibration modes of liquid‐filled conical tanks and validation of a numerical model

Abstract

AbstractTruncated conical‐shaped shells are widely used as containment vessels in elevated water tanks. In the aftermath of earthquakes, water tanks play a vital role in supplying the water needed for extinguishing fires that usually occur during these catastrophic events. As such, special attention has to be given when designing water tanks in order to assure safety and functionality of these structures during a seismic event. To the best of the authors' knowledge, this paper reports the first experimental program conducted to evaluate the dynamic characteristics of liquid‐filled flexible conical shell structures. A small‐scale aluminium conical shell model was mounted to a shaking table and subjected to a set of dynamic excitations. In the first phase of the experimental program, acceleration measurements were used to identify the first two modes of vibration. In the second experimental phase, the cos(θ)‐modes were identified through base shear and overturning moment measurements. The study was also conducted analytically using a numerical model that was previously developed by El Damatty et al. The model accounts for the effect of the added mass resulting from the developed hydrodynamic pressure through a proper fluid–structure interaction formulation. Tests conducted in the two experimental phases were simulated using this numerical model. In general, the experimental and analytical predictions of the dynamic characteristics of the tested model were in very good agreement. This provides a validation of the previously developed numerical model. The analytical model was then implemented to assess the generalized added mass of the contained fluid. Copyright © 2003 John Wiley & Sons, Ltd.