Static Tilt Analyses of Uplifting Cylindrical Tank

by David T. Lau, Carleton Univ, Canada,
Ray W. Clough, Carleton Univ, Canada,

Document Type: Proceeding Paper

Part of: Seismic Engineering: Research and Practice


This paper describes the general method adopted for predicting the static tilt performance of cylindrical liquid storage tank that is free to uplift. In the analysis described here, the base plate, subjected to both membrane tension and plate bending, is divided into the contact and the uplifted regions. The deformations of the bottom plate are evaluated by a Ritz-type method, using iteration to determine the boundary of the contact region, full continuity is maintained with the tank wall. The cylindrical tank shell is analyzed by using Flugge thin shell theory, and its stiffness is cast in a form comparable with that of the base plate for direct stiffness summation. The stiffening effects of the top rim wind girder and bottom toe ring are also included. Friction exerted along the bottom edge of the shell still in contact with the platform is modeled by lateral support springs the stiffness of which is 'fine tuned' to model the frictional forces. Using this analytical approach, the responses of two model tanks (one broad and one tall) to various angles of tilt are evaluated, and the results are compared with measured data. The differences in uplift behavior between the broad and tall tank models are discussed. Finally, the sensitivity of the uplift behavior to various parameters characterizing the tank system is studied.

Subject Headings: Cylindrical tanks | Plates | Stiffening | Statics (mechanics) | Uplifting behavior | Friction | Structural behavior | Storage tanks

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