Enhancement of Uplift Displacement of Tanks due to Out-of-Round Deformation of Cylindrical Shell

Abstract

Abstract Two unanchored vinyl chloride scale tank models, whose diameter, height and thickness of their shell and base were 860 mm, 400 mm and 0.5 mm respectively, were set on a shaking table for experiencing the horizontal motion. These scale tank models satisfy law of similarity to have an equivalent strain under the action of loads. The first scale tank model has no stiffeners on its cylindrical shell that allows out-of-round deformation of the cylindrical shell during the shaking table test. To understand effects of the out-of-round deformation of the cylindrical shell on the tank uplift, the sweeping test is carried out. The Operational Modal Analysis clarifies that the out-of-round deformation of the cylindrical shell enhances the uplift displacement by denting a part of cylindrical shell. The second scale tank model has the multi-stage stiffeners on its cylindrical shell to prevent its out-of-round deformation during the shaking table test. The primary purpose of the second test is to verify applicability of the explicit finite element analysis for analyzing the tank rocking motion. The time history of the uplift displacement of the tank base during a seismic excitation is measured and compared with that computed by the explicit finite element analysis. The comparison shows that the explicit finite element analysis adequately reproduces the tank rocking behavior.