AbstractIn order to design efficient and highly utilised sections, the plastic/plastic design approach depicts a valuable tool. Concerning plastic design, Eurocode 3 requires only Class 1 cross‐sections and material grades up to S460, depicting conventional strength steels (CSS), to be used. High strength steels (HSS) with yield strengths up to 700 MPa are not considered appropriate for plastic design due to their lower ductility. However, the exclusion of HSS appears to be unnecessary in the light of recent test results. Experimental investigations on 20 homogeneous and hybrid high strength double symmetric I‐section beams have been conducted comprising various slenderness characteristics of flange and web and different span lengths. The results show that the rotation capacity value of R = 3, currently required by EC3 regulations, can actually be achieved by high strength steel beams depending on their cross‐sectional characteristics. Additionally, the experimental tests have been recalculated numerically. The material characteristics of the models have been defined by flow curves, which have firstly been calibrated on the basis of small‐scale tensile tests and furthermore slightly fitted to the full‐scale test results. Ductile material failure in terms of crack initiation and evolution is considered by incorporating a damage mechanics model. It can be shown that experimental and numerical results show very good accordance.