On the analysis of vertical circular cylindrical tanks under earthquake excitation at its base

The work presented in this report is based on two design standards, which follow an international design philosophy. Eurocode 8 Part 4 - Tanks, Silos and Pipelines, and API Standard 650 - Seismic Design of Storage Tanks. Both are mainly based on the work of Haroun-Housner and Veletsos. Basic assumption is that under seismic excitation liquid containing circular cylindrical tanks move like cantilever beams. This means that the deformation of the cross-section is neglected. The given design formulae are based on nearly 40 years research. But it is difficult or even an impossible task to understand their physical background. Therefore, both design provisions are analysed, dismantled, and guidelines of applicability are presented in this report. Furthermore, the fundamental frequencies of the tank-liquid-system are calculated by a new method, taking into account the shell modal forms, abadoning the cantilever beam model. The new results differ significantly from those calculated by both Eurocode 8 and API Standard 650. It becomes obvious that the basic assumptions for current design provisions are no longer sustainable under the present knowledge of shell design. Therefore they must be overthought. (orig.)Available from TIB Hannover: RR 7409(2000,2) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman