Fabricated Tubular Steel Columns

The Newton-Raphson iterative technique is used to model the strength and behavior of axially loaded, fabricated, tubular, steel columns. Such columns characteristically have highly variable section properties along their length, due in part to the residual stresses introduced by the longitudinal welding process. The analysis developed is used to derive a new set of column buckling curves for columns having the maximum permissible initial out-of-straightness. The curves derived show the dependence of ultimate column load on circumferential location of longitudinal welds. It is also shown that the analysis may be used to accurately model the strength and behavior of real fabricated tubular columns, as tested, provided that some consideration is given to eccentricity of load application and to any rotation resistance of end conditions.