RESEARCH ON THE BEHAVIOR OF STEEL-CONCRETE COLUMNSIN FIRE CONDITIONS

Steel-concrete is a composite material that combines the high strength of steel with the ductility of concrete. This synergy results in improved performance characteristics, particularly for structures subjected to significant static or dynamic loads under fire conditions.In modern construction, steel-concrete composite structures have considerable potential,especially in the design of high-rise buildings, bridges, industrial facilities, as well as in post-conflict reconstruction of damaged infrastructure. The combination of steel frame elements and concrete infill not only reduces the size of structural components but also increases their durability, load-bearing capacity, and fire resistance.The aim of this article is to investigate the behavior of steel-concrete columns under standard fire temperature regimes. The study focuses on analyzing the changes in thermal properties of steel and concrete at elevated temperatures, which significantly affect the load-bearing capacity of the structure. A numerical method based on the finite element approach was used to assess the fire resistance of concrete-filled steel tube (CFST) columns, accounting for the nonlinear behavior of materials over time and space. The research examines the influence of column geometry, cross-sectional shape, and thermal properties of the steel casing on the ultimate performance of the structural element. It was determined that the analyzed CFST column satisfies fire resistance class R 90.The research findings can be applied in the design of fire-resistant load-bearing elements for critical infrastructure facilities.Keywords:steel-concrete, fire resistance, testing, column, composite, temperature.