Steel portal frames usually employ doubly symmetric I-sections for their columns and rafters, which are jointed utilising haunches, thus accommodating the high bending moments that develop at the eaves and apex and resulting in smaller member sections. I-sections are susceptible to lateral torsional buckling due to their open nature, thus necessitating the use of stays and increasing the amount of material and labour required in this type of structures. Replacing I-section columns for tubular square hollow sections (SHS) can lead to significantly lighter structures as the latter ones have greater torsional stiffness and therefore are not susceptible to lateral torsional buckling, whilst they also possess higher resistance to minor axis buckling. The present paper reports the weight savings that could be achieved in various portal frame spans and heights by replacing an I-section column for a SHS column which can be up to around 40%. Employing tubular columns complicates the design and construction of connections. To overcome this problem, this paper also presents novel connections utilising additively manufactured components, which are able to transfer bending moments from the I-section rafters to the SHS columns for various portal frame sizes. The connections have been developed using generative design, a computer based technology that generates optimised 3D models whilst minimizing weights and maximising structural performance. A feasibility study for 3D printing the proposed geometrically complex connections using wire arc additive manufacturing is presented in the present paper.