Overall Buckling of Q460 Welded T-Section Compression Members with Large Slenderness Ratios under Varied Loading Positions

Abstract To investigate the ultimate overall buckling capacity of members loaded through the shear center with Q460 high-strength steel welded T-sections, three welded T-section members with slenderness ratios of 61, 82, and 102 were fabricated from Q460 high-strength steel plates, and quasi-shear-center tests were conducted with measured eccentricities of 19, 15, and 48 mm, respectively. The initial geometric imperfections and residual stresses of the members were measured in the tests; the buckling failure modes were analyzed, and the ultimate overall buckling capacity was obtained. A finite-element model (FEM) considering initial imperfections was established based on the measured data. Geometrically and materially nonlinear analysis with imperfections (GMNIA) was adopted for finite-element simulation, and the correctness of the FEM was verified by comparing the analytical results with the test results. With the aid of the FEM, the ultimate overall buckling capacity of welded T-section compression members with various cross-sectional dimensions and slenderness ratios was also calculated. The results indicated that Q460 high-strength steel welded T-section members loaded through the shear center with larger slenderness ratios undergo overall flexural buckling, while axially compressed and eccentrically compressed members experience overall flexural-torsional buckling. The overall buckling capacity of narrow-flange section compression members under shear-center compression was generally higher than that under axial compression. Therefore, in design, efforts should be made to ensure they are under shear-center compression. For compression members with medium-flange and wide-flange sections, efforts should be made to ensure they are under axial compression in design. The research conclusions are based on specific cross-sectional types and a slenderness ratio range ( λ y ≥ 80 ), which can provide a reference for the rational design of Q460 high-strength steel welded T-section compression members.