The use of web openings in I-section beams has become increasingly common in recent years, and these elements can be observed in various civil engineering applications. This design approach results in an improved weight-to-stiffness ratio in steel beams, enabling their use over longer spans without a significant increase in material cost and deflections due to self-weight. It also avoids the cutting of holes in inappropriate locations for electrical, hydraulic, and air conditioning installations. Steel beams fabricated with web openings also represent an important solution when height constraints are imposed on multi-story buildings due to design regulations and economic considerations. It is recognised that the use of the traditional web opening shapes - namely, circular, rectangular, and hexagonal - in civil structures can lead to issues associated with high stress concentration. The presence of these web openings can induce local instability or yielding due to inadequate shear force transfer across the openings, allowing plastic hinge formations, also known as Vierendeel mechanism, for instance. In this sense, researchers have investigated novel shapes to mitigate the impacts of the web openings in both structural and economic terms. In this sense, this work has been developed aiming to evaluate the structural performance of I-section beams obtained using structural optimisation, for a reference distributed load and different boundary conditions, compared with the cellular beams. An evaluation of the structural potential of the obtained topologies has been performed by linear elastic, buckling and complete nonlinear analyses. Results were obtained in terms of stresses, displacements, and ultimate loads for all investigated cases. It was found that when compared to a cellular beam, the optimised beams increased the ultimate resistance with superior stiffness resulting in lower displacements and presented a more adequate stress distribution with lower stress concentration. However, in some cases a poor structural performance was observed due to large zones with holes obtained from the optimisation process. Based on these results and on the work of Tsavdaridis et al., authors proposed a configuration for the openings, and its structural performance proved it to be a promising solution to be employed on beams with web openings, especially when the expected failure mode is lateral-torsional buckling. A parametric study was conducted to assess the efficiency of the proposed configuration for different steel profiles and span lengths; results indicated equivalent or superior load capacity when compared to the reference cellular beam. The configuration suggested by the authors can be easily fabricated, and, considering the constant patterns along the length, finding an expression to determine its design load is possible, like what is usually done for other shapes (circular, hexagonal).