A review of buckling capacity of steel cylindrical shells under external pressure: reinforcements and imperfections (2005-Present)

Steel cylindrical shells subjected to external pressure are fundamental components in various engineering applications, including pipelines, and storage tanks. The buckling evaluation of these structures is critical, particularly under complex conditions involving reinforcements, imperfections, and multiple force interactions. This review paper synthesizes advancements in the field from 2005 to the present, focusing on reinforcement techniques and the effects of geometric imperfections on structural performance. Reinforcement strategies are explored, including circumferential and longitudinal stiffeners, corrugations, carbon fiber-reinforced polymer (CFRP) composites, stepwise thickness variations, and the influence of global confinement. The impact of geometric imperfections, such as welding defects, ovality, waviness, dents, and their interaction with shell proportions (L/R and R/t ratios), is systematically analyzed, with particular attention to long shells, thick-walled tubes, and corrosion effects. The paper also touches on studies where external pressure is combined with other loads (such as internal pressure, axial compression, or bending) to simulate realistic multi-loading scenarios. The findings highlight the significance of understanding these multifaceted interactions for improving design and safety standards. This comprehensive review provides a valuable resource for engineers and researchers working to optimize the performance and reliability of steel cylindrical shells under challenging operational scenarios.