Seismic Analysis of Fluid Storage Tanks

Refinements are presented on a model proposed originally by Wozniak for the seismic analysis of fluid storage tanks, which forms the basis of the provisions in the American Petroleum Institute design code API 650. It is found that use of the rules in API 650 may lead in some cases to underestimations of the maximum compressive stresses in the shell, and to overestimations of the tensile stresses in the straps of anchored tanks. The stiffness of these straps relative to that of the shell is shown to play an important role in the maximum compressive stresses that can be expected in the tank wall. In the case of unanchored tanks, the larger compressive shell forces result from the limited mass of fluid that can be mobilized before the buckling load in the shell is reached.