Buckling of Cylindrical Steel Tanks With Oblique Body Imperfection Under Uniform External Pressure

Shell structures are built using a number of welded curved panel parts. Hence, some geometrical imperfections emerge. These imperfections have a direct impact on structural behavior of shells during the external compressive loading. In this research, a field study was accomplished on the implementation of the storage tanks in a refinery site, and then the resulted imperfections were identified and categorized. The survey of imperfections revealed that imperfection resulted from deviation with respect to the vertical direction has the highest number in tank bodies. This imperfection experimentally modeled, and the buckling behavior of these tanks was evaluated under uniform external pressure. The cylindrical tanks were examined using finite element analysis, and results obtained were compared with experimental results. Investigation of finding results demonstrated that such imperfection has a significant role in reducing the number of circumferential waves in body of the tanks under uniform external pressure. Comparing the results obtained by estimation, American Society of Mechanical Engineers (ASME) code, experimental research, and finite element method (FEM) represented a considerable difference in the amount of buckling load. Results show that tanks with oblique body imperfections exhibit high initial strength against buckling due to the uniform external pressure.