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This paper describes an experimental study on the behavior of load-bearing cold-formed steel (CFS) members under elevated temperatures from fire exposure. A custom-built electrical furnace with six independently controlled heating zones was installed in a loading frame, enabling testing of CFS members under uniform or non-uniform elevated temperatures. The ability to precisely control temperature gradients between the flanges allows testing a single member to failure under thermal conditions representative of a wall assembly exposed to fire on one side, capturing the effect of thermal gradient on the buckling behavior. Steady-state tests on short (18 in.) 600S200- 54 lipped channels in compression were conducted at temperatures up to 600 °C, including tests with uniform temperatures and tests with 100°C gradient between the two flanges. Coupon tests were also conducted to characterize the material properties at elevated temperatures. The members lost about 23% of their strength at 400°C and 66% at 600 °C. For these short specimens under nonuniform heating, with one flange 100°C hotter than the other, the member strength fell between the strengths associated with the temperatures of the hot and cold flanges, with limited asymmetric effect on the local buckling response. This experimental data can support the development of design methods for CFS members in fire, enabling performance-based fire design.
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This content will become publicly available on April 4, 2026
Numerical modeling of the post-earthquake fire performance of cold-formed steel members
The objective of this paper is to investigate the post-earthquake thermal-mechanical response of cold-formed steel (CFS) members. A 10-story cold-formed steel building (CFS-NHERI) will undergo seismic tests, followed by post-earthquake live fire tests. To support the fire test setup, computational models are developed to simulate the impact of varying post-earthquake damage levels on the fire response of the structure. As a panelized system, damage to different finish and nonstructural systems significantly affects the thermal behavior and load-bearing capacity of the CFS components. The computational models integrate the modeling capability in CUFSM and SAFIR for the elastic buckling, heat transfer, and transient structural analysis under fire. A parametric analysis considering different seismic damage levels is conducted to study the buckling and strength behavior of the CFS members under fire-induced nonuniform temperature fields. These pre-test models inform the duration and severity of the fire tests to maintain structural stability while achieving substantial thermal loading on the CFS load-bearing system. They also provide guidance for the sensor layout plan for the fire tests. This study advances methods for fire resilience of thin-walled CFS structures under multi-hazard scenarios.
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- Award ID(s):
- 2237623
- PAR ID:
- 10587700
- Publisher / Repository:
- 2025 Proceedings of the Structural Stability Research Council Annual Stability Conference
- Date Published:
- Format(s):
- Medium: X
- Location:
- https://files.ssrcweb.org/proceedings/2025/Niu_et_al_SSRC_2025.pdf
- Sponsoring Org:
- National Science Foundation
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