Evaluating Local Buckling Strength of HSB460 Steel Tubular Columns

Abstract

High performance steels for bridges (HSB), as adopted by the Korean Design Standard (KDS), having a yield strength greater than 350 MPa have recently been developed. Notably, HSB460, which has a minimum yield strength of 460 MPa, does not exhibit a yield plateau beyond yielding and exhibits strain hardening. Such characteristics could provide advantages by absorbing the greater strain energy of steel members and increasing the local buckling strength, which may help develop more economic bridge designs. However, the current KDS for compression members of steel tubular columns was established based on the results of axial load tests for conventional structural steel having yield strengths from 250 to 350 MPa, which exhibits a yield plateau. Three-dimensional finite element analyses adopting actual stress-strain curve of HSB460 were subsequently carried out to evaluate the buckling strength, by considering the ovality, welding residual stresses, and the cross-section sizes. It was confirmed that HSB460 steel tubular columns could have larger margins compared to the current KDS, primarily due to advantages from strain hardening with no yield plateau. As such, with regards to local buckling, the proposed design guidelines for HSB460 steel is expected to enable a more economic bridge design.