Abstract: In order to analyze the failure reasons of a steel single-layer spherical reticulated shell structure with fixedroof on one 20,000 m³ internal floating roof tank, the chemical composition and mechanical properties of the failure structure materials were analyzed. The results show that the sulfur content of the rod end castings of the hub joint, elongation after fracture and shrinkage after fracture of the test sample did not meet the requirements of relevant standards. Using the general finite element analysis software, the strength, stiffness and stability of the reticulated shells under design and failure conditions were analyzed respectively. And the analysis results indicate that the length to slenderness ratio of some members exceeded the design specification requirements, and the actual stress value of the member at the end of the rod exceeded the design value of the tensile strength of the material under failure conditions, which resulted in the strength failure of the structure.

Key words: tank roof reticulated shell, hub joint, mechanical properties, failure analysis