Bifurcation Buckling of Aboveground Oil Storage Tanks under Internal Pressure

Author(s):  
S YOSHIDA
Author(s):  
Shoichi Yoshida ◽  
Kazuhiro Kitamura

The 2003 Tokachi-Oki earthquake caused severe damage to oil storage tanks due to liquid sloshing. Six single-deck floating roofs had experienced structural problems as evidenced by sinking failure in large diameter tanks at the refinery in Tomakomai, Japan. The pontoon of floating roof might be buckled due to circumferential bending moment during the sloshing. The content in the tank was spilled on the floating roof from small failures which might be caused in the lap-welded joints or in the stress concentrated parts of the pontoon bottom plate by the buckling. Then the floating roof began to lose buoyancy and submerged into the content slowly. The failure of the roof expanded gradually in the sinking process. It is presumed that the initial small failures were caused by the elastic buckling of the pontoon due to circumferential bending moment. In this paper, the buckling strength of the pontoon is presented using axisymmetric shell finite element analysis. Linear elastic bifurcation buckling analyses are carried out and the buckling characteristics of ring stiffened pontoons are investigated.


2003 ◽  
Vol 125 (1) ◽  
pp. 78-84
Author(s):  
Seiya Hagihara ◽  
Noriyuki Miyazaki

Cylindrical tanks with conical roof shells are utilized as oil storage tanks and for some containment vessels. It is known that conical roof shells and torispherical shells subjected to static internal pressure buckle into a displaced shape with circumferential waves caused by an instability condition commonly called bifurcation buckling. It can be important to obtain the dynamic bifurcation buckling load in designing conical roof shells. In this paper, the bifurcation buckling pressure is calculated for dynamic pressure during accident conditions as characterized by step pressure loading, ramp pressure loading and pulse pressure loading. The minimum bifurcation buckling pressure is shown to be a linear function of radius-to-thickness ratio R/h of the shell in a linear fashion on a logarithmic scale. The minimum bifurcation buckling pressure is minimum for conical roof shells subjected to the step loading. The minimum dynamic bifurcation buckling pressure for step loading is about half of the static bifurcation buckling pressure.


1997 ◽  
Vol 15 (7-8) ◽  
pp. 755-764 ◽  
Author(s):  
S.A. Fazal ◽  
R. Rai ◽  
G.C. Joshi
Keyword(s):  

Author(s):  
Shoichi Yoshida

Floating roofs are widely used to prevent evaporation of content in large cylindrical aboveground oil storage tanks. The 2003 Hokkaido Earthquake caused severe damages to the floating roofs due to sloshing. These accidents became a cause to establish structural integrity of the floating roof tanks in sloshing. However, many designers do not have a solution for the sloshing of floating roof tanks except for three-dimensional FEA computer codes. The three-dimensional FEA requires a long computational time and expenses. The sloshing of floating roof tanks is a coupling vibration problem with fluid and structure. The simplified and convenient method has been desired for this solution. This paper presents a simplified development method of a FEA code in the axisymmetric linear problem. It is performed to modify an existing structural analysis code. The fluid behavior is formulated in terms of displacement as the Lagrangian approach.


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