External Pressure and Sectional Behavior of Fabricated Tubes

The effect of external hydrostatic pressure on the cross sectional behavior of fabricated tubular columns is studied analytically using tangent stiffness approach. The moment-curvature behavior of a short column is of prime importance in the analysis of any long beam-column. The results will be applied to study the effect of external pressure on the strength and behavior of long beam-columns. The fabricated tubular column contains imperfections such as out-of-roundness and longitudinal and transverse residual stresses. These imperfections combined with the effect of external pressure are studied in the present analysis. Tresca yield criterion is used for elements in biaxial stress state, which is induced by the interaction of axial stress and longitudinal and transverse residual stresses and magnified by external pressure. A computer program has been developed to obtain numerical results from which practical design formulas are derived for cross-sectional capacity of fabricated tubular columns subjected to axial force, bending moment and external hydrostatic pressure.