Experimental and numerical investigation of stress in a large-scale steel tank with a floating roof

Research on steel tanks, particularly large-scale oil storage tanks, has increased significantly with the rapid development of the petrochemical industry. The focus on these thin-walled structures is related not only to the cost of the infrastructure, but also because failures due to accidents may generate huge economic costs, environmental losses, and casualties. The aim of the present study is an extensive experimental and numerical investigation of stress in a large-scale oil tank with a floating roof. Stresses in the shell and bottom of a large-scale oil storage tank are measured by a resistance strain gauge technique. Meanwhile, an improved 3-D finite element model is developed to analyze stresses in the tank. By comparing calculated results with experimental data, the validity of the developed finite element model is verified. Both experimental and numerical results suggest that the stress on the fillet joint is relatively high in the tank. The finite element model is used to study the effects of three key steel tank parameters on the stress of the fillet joint in the oil storage tank: the thickness of the annular bottom plate at the base, the radial width of the projection of the annular bottom plate outside the shell, and the radial width of the concrete ringwall. In addition, a new method related to the design of the annular bottom plate and concrete ringwall is proposed. This method will be helpful in improving the design of large-scale oil tanks and assessing their structural integrity.