Simplified seismic analysis procedures for elevated tanks considering fluid-structure-soil interaction

This paper presents a review of simplified seismic design procedures for elevated tanks and the applicability of general-purpose structural analyses programs to fluid-structure-soil interaction problems for these kinds of tanks. Ten models are evaluated by using mechanical and finite-element modelling techniques. An added mass approach for the fluid-structure interaction, and the massless foundation and substructure approaches for the soil-structure interactions are presented. The applicability of these ten models for the seismic design of the elevated tanks with four different subsoil classes are emphasized and illustrated. Designers may use the models presented in this study without using any fluid and/or special soil elements. From the models defined here, single lumped-mass models underestimate the base shear and the overturning moment. Because almost all the other assumptions for the fixed base give similar results, any method could be used, but the distributed added mass with the sloshing mass is more appropriate than the lumped mass assumptions for finite-element modelling, and is recommended in this study.