Buckling Behaviors Of Steel Silos Subjected To Combined Loading Of Overall And Local Axial Compression

As a thin-walled shell structure, the failure modes of the steel silo include strength failure due to the horizontal pressure of storage and stability failure due to the vertical load. Abruptness of failure, small stress and sensitivity to the type of initial imperfection for the stability failure make it the main part of steel silo design.A set of numerical studies consist of four load cases including 1) uniform load on the top of the silo; 2) uniform load on the top of the silo and inner pressure; 3) partial load on the top of the silo; as well as 4) uniform load and partial load on the top of the silo, using finite element program ABAQUS, were carried out to study the buckling behavior of silos. Analysis methods adopted includes linear buckling analysis, geometric non-linear buckling analysis, as well as geometric and material non-linear buckling analysis. Circumferential weld geometrical imperfection was considered and the influence of the location of the imperfection, distribution of the imperfection, magnitude of the imperfection as well as the number of imperfection on the buckling behavior of silos were investigated. Parameters about the silo include the radius to thickness ratio and the steel strength.The influences of magnitude of imperfection, location of imperfection, radius to thickness ratio as well as steel strength on the buckling modes and load-displacement curves of silos subjected to a uniform load were investigated numerically. Results showed that all of the parameters except location of imperfection had a significant effect on the critical load of silos subjected to a uniform load. Based on the numerical results, a practical design equation for the critical load of silos subjected to a uniform load was proposed.Buckling behaviors of silos subjected to a uniform load and inner pressure were investigated using finite element analysis. Parameters studied included radius to thickness ratio, steel strength and the magnitude of inner pressure. Results indicated that silos subjected to elastic buckling failure and the critical load increased with the increase in the inner pressure when a small inner pressure was applied to the silos. However, silos were vulnerable to elastic-plastic buckling failure and the critical load decreased with the increase in the inner pressure when a large inner pressure was applied to the silos. Finally, a practical design equation for the critical load of silos subjected to a uniform load as well as inner pressure was proposed based on the parametric study.Buckling behaviors of silos in which the circumferential weld geometrical imperfection was incorporated subjected to a partial load were investigated. Buckling modes, load-displacement curves, buckling stresses, and the most unfavorable location of imperfection with different load distribution angles were analyzed. Besides, the influences of the magnitude of imperfection, steel strength on the buckling load were studied. It was found that load distribution angles had a significant influence on the critical buckling load. Finally, a practical design equation for the critical load of silos subjected to a partial load was proposed.Buckling behaviors of silos subjected to a uniform load as well as a partial load were investigated using finite element method. The ultimate partial load of the silos under different levels of uniform load was investigated. Parameters considered included load distribution angle, magnitude of imperfection, location of imperfection and steel strength. It was found that the uniform load level and partial load distribution angle had a great influence on the critical load and the most unfavorable location of imperfection. Finally, a practical design equation for the critical load of silos subjected to a uniform load and a partial load was presented.