Wind-Induced Buckling and Load Capacity of a Large Floating-Roof Tank Under Nonuniform Settlement

Large storage tanks are often constructed in coastal areas with relatively poor geological conditions, where foundation settlement and strong wind loads pose significant challenges to safe operation. This study investigates a 100,000 m3 large external floating-roof storage tank. A three-dimensional shell finite element model is established, and geometrically nonlinear analysis combined with the arc-length method is employed to investigate the effects of liquid level, wind direction, and settlement characteristics on the structural response and wind-resistant stability of the tank. The results show that nonuniform foundation settlement changes the initial geometry of the tank wall and causes pronounced circumferential stress redistribution near the bottom edge. The overall radial deformation of the tank is governed primarily by the settlement-induced initial deformation, whereas the additional displacement caused by wind loading is relatively small but strongly direction-dependent. As the liquid level increases, the critical wind load factor increases, and the governing buckling region shifts toward the middle and upper portions of the tank wall. The maximum critical wind load factor among the investigated wind directions is 32.31% higher than the minimum value. When the settlement amplitude increases to approximately 1.5 times the measured value, the wind load-carrying capacity begins to deteriorate at a markedly accelerated rate. In addition, settlement amplitude, harmonic order, maximum slope, and curvature jointly affect structural stability. Under the same settlement amplitude, higher-order settlement components with shorter circumferential wavelengths are more likely to cause localized bending deformation. Therefore, settlement amplitude, circumferential slope, curvature, harmonic composition, and wind direction should all be considered in the inspection and wind-resistance assessment of large storage tanks.