Assessment of Resistance Models According to SIA 263 & Eurocode 3 Provisions for Lateral Torsional Buckling of I-Shaped Hot-Rolled Members

In the European and Swiss steel construction standards, the stability verification of steel beams against Lateral Torsional Buckling (LTB) is considered with a decrease in bending resistance, reflected in reduction factors drown from buckling curves. In the case of hot-rolled profiles, the standards exhibit significant differences between one another, both in terms of formulations and results, which differ up to 12% relatively to the beam resistance. Moreover, in the line of recent developments, a new LTB assessment method is provided in the reviewed version of the European norm. In the face of such contrasts, the accuracy, consistency, and safety of the formulations are naturally questioned. In this paper, after reporting on the state of theoretical knowledge and research around LTB, a numerical modelling procedure is detailed and automated to exhaustively trace the theoretical numerical buckling curves of hot-rolled profiles. Based on these results, the estimated curves from the standards are evaluated and compared, highlighting the net superiority of the new formulation. Then, the work is repeated with different, more refined parameters, namely material constitutive law, and residual stress profiles, allowing to both evaluate the model sensitivity to these parameters and re-assess the codes’ accuracy.