Dependence of the fire resistance limit of a steel column on the load level

Sidnei Stanislav

National University of Civil Protection of Ukraine

https://orcid.org/0000-0002-7664-6620

Ishchenko Ivan

National University of Civil Protection of Ukraine

http://orcid.org/0009-0000-5050-4926

Kostenko Tetiana

National University of Civil Protection of Ukraine

http://orcid.org/0000-0001-9426-8320

Motrichuk Roman

National University of Civil Protection of Ukraine

https://orcid.org/0000-0002-5670-6788

Shkoliar Ievgenii

National University of Civil Protection of Ukraine

http://orcid.org/0000-0002-7304-1677

Koloskov Volodymyr

National University of Civil Protection of Ukraine

http://orcid.org/0000-0002-9844-1845

DOI: https://doi.org/10.52363/2524-0226-2025-42-17

Keywords: fire resistance, finite element method, computer modeling, loss of load-bearing capacity, fire

Аnnotation

The object of the study is the stress–strain state of an unprotected steel column under the combined action of thermal and mechanical loading. The research problem lies in the absence of a simplified approach in modern engineering practice for assessing the fire resistance of steel columns that would provide an acceptable level of accuracy comparable to the results obtained through advanced numerical modeling methods. The application of such advanced methods requires significant computational resources, specialized software, and a high level of technical expertise. This makes them difficult to use during time-constrained design processes or for real-time risk assessments in practical conditions. Therefore, there is a need for a more accessible engineering tool capable of predicting the loss of load-bearing capacity of steel structures under fire exposure with sufficient accuracy, without relying on complex calculation schemes. As part of the research, calculations were performed to assess the fire resistance of an I-section steel column (section № 24) subjected to standard fire conditions in accordance with ISO 834, taking into account different levels of applied mechanical loading. The mathematical modeling was conducted in the ANSYS Workbench software environment, which made it possible to incorporate temperature-dependent material properties, the spatial geometry of the element, and the combined effect of thermal and mechanical loads. These calculations provided the basis for developing an analytical dependence of the fire resistance limit on the level of applied load. The proposed relationship ensures high accuracy, comparable to that of detailed numerical methods, while enabling a rapid assessment of the fire resistance of similar structural elements without the need for complex simulations, which typically require substantial computational capacity and specialized personnel. Thus, the results of the study formed the foundation for a practically oriented approach to the preliminary determination of the fire resistance limit of steel columns based on a known load level.

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