Beam-column Resistance of Steel Members: A Comparative Study of Aisc Lrfd and Ec3 Approaches

The paper presents a comparative study of a well-established steelwork design standard, the American AISC LRFD, and the new European code for the design of steel structures, Eurocode 3. The study is focused on the resistance capacity of steel members subjected to one of the following load cases: axial compression, bending, and combined axial compression and bending. First, the paper compares the formulation of both codes in order to identify similarities and differences. Particular attention is given to the resistance of beam columns since many steel structural members in building structures fall into this category. In the case of pure bending and combined axial compression and bending, the paper considers two extreme cases of linear moment distribution: equal end moments and opposite end moments. The results are presented graphically in order to make possible their interpretation and to detect significant differences in resistance. The comparative study shows that the resistance capacities given by LRFD and EC3 can differ appreciably for some of the cases considered. Moreover, there are also significant differences between the two methods proposed by the Eurocode when slenderness is high and the beam is subjected to linear moment distribution with opposite end moments. Finally, the paper stresses those points where each standard offers a simpler approach.