End Restraint and Column Stability

In connection with the widespread tendency toward base-column design in the future on the strength not of ideally straight, but of initially crooked columns, it is of considerable importance to clarify the influence of end-restraints on such columns, whose strength, so far, was most investigated from the hinged-hinged end conditions. Numerical studies have shown that initial crookedness and residual stresses can significantly reduce the strength of hinged-end columns. This is reflected most notably in the recent development of multiple column strength curves. The effect of these two factors is not so clearly understood, however, for the more realistic case of columns with partially restrained ends. This paper attempts to identify this important problem which requires fundamental research; it provides the needed background information, defines the basic problem in some detail, and describes the current research effort on this subject by the Structural Stability Research Council.