Finite element analysis of the roof latticed shell structure for largescale single capacity LNG tank

For a large-scale single capacity LNG tank, non-uniform and non-symmetrical load distribution exits on its roof. Taking the roof of a 3×10⁴ m³ metal double-wall LNG tank as a research object, a finite element model of the 45.2 m (diameter) roof with ribbed single-layer dome structure is established. In accordance with relevant standards, the loads are applied to latticed shell structure according to the actual load distribution. The finite element analysis of strength, stiffness and overall stability of the latticed shell structure is performed under 28 kinds of load conditions. The results show that the latticed shell has the largest stress of 273.07 MPa under the combination of constant load and the designed internal pressure load, while it has the maximum vertical displacement of 31.02 mm under the combination of constant load and live load. The safety factor of latticed shell is 6.372 and the overall shell is safe and reliable. Nonlinear analysis results show that global instability point appears in the largest local load of pump well location when the latticed shell loses stability. The local load must be considered when the static and stability analysis is conducted, which plays an important role on the overall instability of latticed shell structure.