Span-Depth Ratios for the preliminary structural design of steel beams: The case of European hot-rolled I sections without lateral-torsional buckling

Preliminary sizing, based on "Shape Ratios" or “Depth-to-Span Ratios”, plays a key role in the design process, both during the conceptual stage and in the validation and verification phases of structural design, representing one of the main index parameters. Shape ratios, whether global or local, are revisited herein as a contemporary reinterpretation of the classical “Theory of Proportions” and can be derived either through structural analogies or by means of parametric analyses that investigate the main variables influencing the demand and capacity of the structural systems under study. Adopting a parametric approach, this work investigates the shape ratios of European hot-rolled narrow-flange I-sections subjected to different boundary conditions (loads and supports) and produced with the principal grades of structural steel. The objective is the validation and disaggregation of the datasets reported in the literature, with the aim of enabling their more reliable and effective use in structural design, both through conventional methods and advanced digital tools, including Building Information Modeling (BIM) environments implemented via parametric families of members or systems. The results allow for the evaluation of alternative design configurations already at the conceptual stage, while also serving as an efficient tool for structural optimization, which can be further enhanced through algorithmic strategies underpinning Artificial Intelligence (AI).