Section slenderness limits of very high strength circular steel tubes in bending

This paper investigates the bending behavior of very high strength (VHS) circular steel tubes. The tested VHS tube has a normal yield stress of 1350 MPa and an ultimate strength of 1500 MPa. A total of 12 specimens, with the normal diameter ranging from 31.8 to 75 mm and the tube thickness between 1.6 and 2.0 mm, were tested. Large bending deflection was achieved for VHS tubes with the diameter to thickness ratio up to 24. Full plastic moment was reached for tubes with the section slenderness of 197 or less. New plastic slenderness limits of 117 and 153 were proposed based on the beam plastic rotation capacity of 4 and 3. A yield slenderness limit of 264 was proposed for VHS tubes.