Optimizing Thin-Walled Structures: Analysis of Cold-Formed Steel Columns with Concrete Infills, Web Stiffeners, and CFRP Strengthening

Current design trends indicate a rising preference for mixed steel-concrete structures, which provide exceptional opportunities for material optimization and numerous advantages, including improved strength, ductility, and stiffness. This trend aligns with the growing demand for sustainable and resilient construction solutions in civil and structural engineering. The present article provides an analytical and numerical investigation focused on enhancing the performance of cold-formed steel back-to-back C-columns through the application of various strengthening materials, including concrete and carbon fiber-reinforced polymer (CFRP) layers. The study employs advanced finite element modeling techniques to simulate real-world loading conditions and incorporates rigorous parametric analyses to evaluate structural behavior under varying constraints. Furthermore, it investigates the impact of incorporating different types of web stiffeners—namely, simple, square, and triangular—on the mechanical behavior of built-up columns subjected to axial compression. The research also explores how these configurations influence load distribution and failure mechanisms. To validate the analytical approaches, the numerical findings are compared with predictions based on EN 1994-one to one standards, allowing for an evaluation of the effectiveness of the formulations in estimating the contributions of individual components. The results indicate that the addition of concrete significantly enhances the strength and lateral stability of built-up empty columns, with improvements of approximately 70% and 75%, respectively. Conversely, the application of CFRP strips leads to a reduction in lateral instabilities by about 80%. Additionally, the combined use of concrete and CFRP materials demonstrates synergistic benefits, offering a balanced enhancement of both compressive strength and lateral stability. These findings provide essential insights for optimizing the design and performance of thin-walled structures in engineering practice. The study emphasizes the practical implications of these results for designing lightweight, high-performance structures that meet modern construction demands.