Cold formed steel semi rigid joints

Abstract

This article presents a theoretical and numerical study of an innovative joint using cold-formed steel sections. The motivation for the study of this connection is the ease of manufacturing and assembly that it provides. The profiles are made of coldformed lipped channel sections, which are welded to form closed built-up sections on the columns and open built-up lipped sections to the beams. The beams use endplates connected by bolts (threaded bars) to the columns. The study evaluates the connection's initial stiffness of 19 models, where the following parameters were varied: the thickness of the profiles and endplates, the height of the column sections and the diameter of the bolts. A theoretical and a numerical study were developed: the numerical study was performed using finite elements through the commercial software ANSYS, whereas the theoretical study was made based on the component method, prescribed by Eurocode 3, that does not include the design of the connection analyzed herein. Thus, aiming to enable the design of joints composed of cold-formed lipped channel sections, the analysis results were compared and an adjustment coefficient, proportional to the slenderness of the column's plates, was proposed. The coefficient was introduced to the stiffness component that represents the column web in compression in the mechanical model. The ratio between the coefficients' numerical and theoretical values presented a maximum variation of 11%, which was considered satisfactory.

Estudo da influência das imperfeições geométricas iniciais no comportamento de pórticos semi-rígidos de aço

“…Para isso, foram realizadas pesquisas sobre o comportamento das ligações representadas por curvas momento-rotação para diferentes tipos de ligações empregadas como em Al-Bermani and Kitipornchai (1992). Atualmente ainda muitas pesquisas são realizadas para aperfeiçoamento do estudo das ligações como, Bahaz et al (2018), Silva et al (2018) que analisa a rigidez inicial de uma junta inovadora composta por seções de aço formadas a frio e Zhao Z et al (2018) em que é proposto um modelo de análise que pode considerar juntas semi-rígidas e inelasticidade ao mesmo tempo com alta precisão, e pode ser convenientemente incorporado no software de elementos finitos em geral.…”