Modeling of haunches in frame structures – implications for node dimensioning

<ns3:p>Steel frame structures are a widely used solution in industrial and commercial construction, where properly designed bar connections play a key role in ensuring effective force transmission and structural continuity. This paper presents a classification of connections commonly used in steel structures and discusses their impact on the load-bearing capacity, stiffness, and deformability of the entire structural system, in accordance with the requirements of the PN-EN 1993-1-8 (EC3) standard. Special attention is given to the modelling of beam-to-column connections in portal frames, with a focus on the eaves joint area, where longitudinal haunches are frequently applied. The aim of this study is to analyse the influence of different modelling approaches for haunches on the distribution of internal forces and the resulting design implications. The importance of accurate joint modelling in the context of structural analysis and design is highlighted, with particular emphasis on safety, reliability, and economic efficiency in the execution of steel structures</ns3:p>