Post-buckling behavior of steel cylindrical shells during earthquakes

The energy input exerted by earthquakes can be a substantial loading effect of earthquakes, whether the structure remains elastic or not. The energy absorption capacity of a structure can be assumed to be a primary source of resistance of structures against earthquakes. The energy input to structures has been found to be a very stable amount which is mainly dependent on the total mass and the fundamental natural period of structure. On the other hand, even after the occurrence of buckling in elements, structures usually develop a considerable amount of energy absorption. Thus, the occurrence of buckling can not be a decisive criterion for the safety in case of seismic loading, compared to the case of gravity loading under which the structure collapses immediately, when the structure loses its static equilibrium. This paper aims to clarify the ultimate seismic resistance of steel cylindrical structures the strength of which is much affected by buckling. The non-linear response analysis was made on free-standing cylindrical vessels subjected to horizontal ground motions. The model was assumed to be a single degree of freedom system with restoring-force characteristics inherent to cylindrical structures influenced by buckling. The damage index was selected to be the maximum deflection of structure. The loading index was selected to be the total energy input to a structure due to an earthquake