Evaluation of the flexural behavior of precast concrete reinforced beams encased with cold-formed steel channels

The construction industry faces the continuous challenge of developing building systems that are simultaneously economical, durable, and sustainable. In this context, precast concrete structures have been increasingly consolidated as an effective solution to meet demands for performance and efficiency. This article presents a numerical–experimental study on concrete beams encased with cold-formed steel channels. As this is an emerging technology, there is still a lack of studies addressing the influence of design parameters on the structural performance of these elements, and no analytical models for their design are currently available in the literature. The main objective of this work was to evaluate the flexural behavior of concrete beams encased with cold-formed steel channels. Three full-scale prototypes were tested, and the experimental results were used to calibrate and validate a finite element model developed in ABAQUS, which was subsequently employed in a parametric study. Insights from both the experimental tests and numerical simulations were used to develop an analytical model for predicting the design flexural resistance of these beams. It was found that failure occurs, in most cases, due to excessive plastic yielding of the tensioned cold-formed steel channels and the main bottom reinforcement. The addition of the steel frame contributed significantly to the strength of the element, resulting in an increase of approximately 60 % in the ultimate capacity of the beam. Finally, the study evidenced that the connection between the steel channels and the concrete, achieved through welded mesh, activates the composite action and enhances the potential application of this technology in precast systems. • Three full-scale precast RC beams with steel channels were tested in bending. • Experimental and numerical analyses assess the flexural response of encased beams. • Composite action is achieved through welded mesh connection between materials. • The steel channel increased beam strength by about 60 %. • Design equations for flexural strength are proposed based on analytical modeling.