Experimental study on column buckling of 420 MPa high strength steel welded circular tubes

• 24 welded circular tubes made of 420MPa steel were investigated experimentally.
• 60 pin-ended columns based on validated FE models were investigated numerically.
• Curve a in GB50017-2003 and Eurocode 3 and formula in ANSI/AISC360-10 can be used.
• A new column curve with an imperfection factor of 0.17 was proposed.

This paper investigates the column buckling performance of welded circular tubes made of 420 MPa high strength steel (HSS). 24 axial compression column tests on specimens with a nominal diameter of 273 mm and thickness of 6 mm were conducted. Initial geometric imperfections including out-of-straightness and loading eccentricity were measured. Experimental results in terms of buckling modes and load-carrying capacities are presented and discussed in detail. Non-linear finite element (FE) models were developed which captured the experimental observations satisfactorily. Based on the validated FE models, further parametric analyses incorporating 60 HSS numerically generated welded circular tubular columns with various section sizes were carried out. The resulting FE and experimental results were compared with the existing column design curves in Chinese, European and American codes. Numerical results showed that the design resistances calculated based on design curve a in both GB50017-2003 and Eurocode 3 and the design formula in the ANSI/AISC 360-10 could be adopted. In addition, to further improve the design efficiency, a column design curve based on Eurocode 3 formulation with a new imperfection factor of 0.17 was proposed for the design of such HSS welded tubular columns.