Structural Optimization and Seismic Qualification for the Design of Cryogenic Storage Tanks

This paper on "Structural Optimization and Seismic Qualification for the Design of Cryogenic Storage Tanks" was presented at the NAFEMS World Congress on The Evolution of Product Simulation From Established Methods to Virtual Testing & Prototyping - 24-28 April 2001, The Grand Hotel, Lake Como, Italy.

Summary

This paper presents a method of analyzing and seismically qualifying cryogenic liquid storage tanks for safety critical applications.
The main purpose of this paper is to provide an economic technique to idealize, assess, optimise and qualify large thin walled flexible tanks structures to withstand extreme dynamic loads including seismic events. The study comprised of a structural appraisal and seismic assessment of a large cryogenic storage tank and uses a combination of scoping calculations (static, frequency and seismic) and linear FE techniques to represent a complex non-linear problem. The approach used upper and lower bound techniques to best represent the composite and non-composite action of the tank when subjected to large dynamic loads. This approach was necessary to structurally optimise, analyze and substantiate the tanks to comply with ASME III and stringent seismic qualification criteria.
The paper does not deal with sloshing effects, a detailed assessment of the holding down arrangement or soil structure interaction effects that are equally important to provide complete seismic qualification of the tanks and other plant items. These have subsequently been addressed using the findings from this study. The techniques described in this paper for this assessment have been subjected to a detailed peer review process. The proposed recommendations to optimise the tank design to meet the seismic requirements and acceptance criteria have been accepted by the tank designer and manufacturer, independent review panel and are endorsed by the regulators.