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<p>The increasing use of cold-formed steel (CFS) in structural applications highlights the need to understand its behavior under elevated temperatures, such as during fire events. While hot-rolled steel has been well-studied, limited research exists on the thermo-mechanical performance of CFS, particularly non-standard profiles like angle, Z, channel, and sigma sections. These thin-walled members are especially prone to buckling, which is further exacerbated by thermal exposure. This research undertakes a detailed examination of the flexural behavior of four distinct CFS cross-sectional profiles namely angle, Z, channel, and sigma subjected to a range of mechanical loading conditions and elevated thermal environments, with temperatures varying from 28&#xa0;°C to 1000&#xa0;°C. Each section was fabricated with a constant thickness of 3&#xa0;mm and evaluated at a uniform member length of 1500&#xa0;mm. Numerical simulations were carried out using the finite element analysis to investigate the structural response under applied loads between 10 kN and 50 kN and segmented lengths of 250&#xa0;mm, 500&#xa0;mm, 750&#xa0;mm, and 1500&#xa0;mm. Key performance indicators, including critical temperature thresholds, failure durations, and deflection magnitudes, were quantified and compared across the different section geometries. The results demonstrate that, for all evaluated cold-formed steel cross-section geometries, an escalation in applied mechanical loading from 10 kN to 50 kN leads to a substantial reduction in both critical temperature thresholds and failure durations. This clearly underscores the pivotal role of load magnitude in accelerating thermal deterioration under fire conditions. The impact is especially significant in sigma and Z-sections, with Z-section members exposed to full-span heating experiencing a dramatic decline in failure time—from 151&#xa0;min at 10 kN to just 8&#xa0;min at 50 kN. Specimens with shorter heated lengths (250&#xa0;mm and 500&#xa0;mm) are characterized by concentrated stress zones and restricted plastic deformation capacity, which precipitate premature yielding and predominantly brittle failure modes. In contrast, longer heated spans (750&#xa0;mm and 1500&#xa0;mm) foster a more homogeneous stress distribution and facilitate extensive plastic deformation, thereby enhancing structural ductility and resilience under combined thermal and mechanical loading conditions.</p>

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Thermo-mechanical performance assessment of cold-formed steel angle, Z, channel, and sigma sections through numerical modeling

  • 期刊论文

  • 发表日期：

    2026年4月1日

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  • M. Prakash,
  • M. Dhanusia Dharani,
  • G. Murali,
  • Siva Avudaiappan,
  • K. Karthikeyan

摘要

The increasing use of cold-formed steel (CFS) in structural applications highlights the need to understand its behavior under elevated temperatures, such as during fire events. While hot-rolled steel has been well-studied, limited research exists on the thermo-mechanical performance of CFS, particularly non-standard profiles like angle, Z, channel, and sigma sections. These thin-walled members are especially prone to buckling, which is further exacerbated by thermal exposure. This research undertakes a detailed examination of the flexural behavior of four distinct CFS cross-sectional profiles namely angle, Z, channel, and sigma subjected to a range of mechanical loading conditions and elevated thermal environments, with temperatures varying from 28 °C to 1000 °C. Each section was fabricated with a constant thickness of 3 mm and evaluated at a uniform member length of 1500 mm. Numerical simulations were carried out using the finite element analysis to investigate the structural response under applied loads between 10 kN and 50 kN and segmented lengths of 250 mm, 500 mm, 750 mm, and 1500 mm. Key performance indicators, including critical temperature thresholds, failure durations, and deflection magnitudes, were quantified and compared across the different section geometries. The results demonstrate that, for all evaluated cold-formed steel cross-section geometries, an escalation in applied mechanical loading from 10 kN to 50 kN leads to a substantial reduction in both critical temperature thresholds and failure durations. This clearly underscores the pivotal role of load magnitude in accelerating thermal deterioration under fire conditions. The impact is especially significant in sigma and Z-sections, with Z-section members exposed to full-span heating experiencing a dramatic decline in failure time—from 151 min at 10 kN to just 8 min at 50 kN. Specimens with shorter heated lengths (250 mm and 500 mm) are characterized by concentrated stress zones and restricted plastic deformation capacity, which precipitate premature yielding and predominantly brittle failure modes. In contrast, longer heated spans (750 mm and 1500 mm) foster a more homogeneous stress distribution and facilitate extensive plastic deformation, thereby enhancing structural ductility and resilience under combined thermal and mechanical loading conditions.