Numerical and Experimental Study on Ultimate Strength of Stiffened Column Under Axial Compression

Six specimens with one Tee-bar stiffener and its attached plating were tested under axial compression to investigate the ultimate strength. The specimens have one longitudinal span and the simply supported boundary conditions at the end edge of loading were produced based on a horizontal test fixture. The initial geometrical imperfections were measured and tensile tests of high tensile steel used in the specimens with different thickness were conducted. The results calculated by FE analysis with true stress-strain curves, average measured thickness and measured initial geometrical deformation could reach a good agreement with experimental results. The ultimate strength calculated with elastic/perfectly plastic curve is approximately 10% larger than that with true stress-strain curve. The reason is that the proportional limit stress of material is significantly lower than 0.2% proof stress for the high strength steel used in specimens. And the occurrence of buckling is earlier than the time that the material enters into plastic stage. As a result, the ultimate strength assessed with elastic/perfectly plastic curve doesn’t always the lowest result and it should be adopted carefully.