Structural design programs are widely used in engineering, but, as they are market-oriented, they often require a paid license and present graphical interfaces that are not very accessible to new users, demanding prior knowledge of technical standards and the software itself, which limits their application in education. In this context, this paper presents the new implementation and update of an open-source extension for the Linear Elements Structure Model (LESM) software, originally implemented in LESM 2.0 for the design of steel structures with I or H sections according to NBR 8800:2008. The extension was adapted for version 3.0 of the program, with the implementation of the updates of NBR 8800:2024, as well as the EN 1993-1-1:2022 and AISC 360:2022 standards. The objective is to offer a free, intuitive, and educational tool capable of designing I and H sections bent about their major axis, generating detailed calculation reports, and presenting utilization ratios according to each standard. In addition, the automatic generation of comparative tables between the results of different standards for each type of load was implemented. The architecture of these implementations was structured based on a generic superclass and specialized subclasses for each design code, enabling an easier implementation of design standards for other steel section shapes in the future. The results obtained with LESM closely matched those obtained from commercial software and show that the implementation was successful, expanding the scope of LESM and encouraging its use both in the education of new professionals and in the job market.