Finite element modelling of a cold-formed steel profile employed in composite ribbed slabs

Abstract

Structural systems comprised by prefabricated flooring systems and/or cold-formed steel members are frequently employed in the construction industry due to their versatility, high strength-to-weight ratio, ease of prefabrication, transportation and assembly on site. The unification of these structural systems motivated the creation of composite ribbed slabs, which were defined in this research as ribbed floor systems in which cold-formed steel members are used as joists, and the space between them is filled with inert elements. During concrete casting, the cold-formed steel members are solely responsible for bearing the construction loads, and, after this phase, the steel elements work partially or completely as rebar reinforcement. As part of this structural system, the Trelifácil® solution is the object of study of this research, which is a prefabricated element comprising a trussed girder coupled to a cold-formed steel formwork by plastic spacers. Although these prefabricated joists have already been used to replace reinforced concrete lattice girders, it was only recently that researchers started looking into the design of these structural elements as well as into the feasibility of considering the composite action between components to achieve an economical design. Therefore, the focus of this research is to develop finite element models using ANSYS® 2020R1 capable of predicting the flexural behaviour of the Trelifácil® solution with and without the trussed girder attached to it. Additionally, the outcome of the finite element analyses aims to support the design of physical tests to validate the modelling techniques employed herein. To develop the finite element models, a variety of studies are conducted to assess the main parameters found in the literature review that may influence finite element predictions. The results indicated that the collapse analyses of the cold-formed steel member are sensitive to boundary conditions, loading position, element choice, mesh density, plasticity model and solution scheme. Based on the literature review, this research presented possible modelling techniques for each of these major issues. In addition, the gains in strength and stiffness found with the suggested finite element model for the entire configuration of the Trelifácil® solution reinforced the potential of this structural system that can be derived through the consideration of composite action between its components.