Hybrid fire testing of concrete-filled steel tube columns: A large-scale experimental and numerical investigation

Hybrid Fire Testing (HFT) integrates experimental fire testing with numerical simulations to better capture the interaction between a physical sample in a furnace fire and the structure that would surround it in real-world conditions. Unlike traditional fire testing, HFT enables a more accurate analysis of complex structural behaviours by simulating the effect of adjacent structural elements, thus providing a realistic assessment of a structure's fire performance. This paper presents a full-scale experimental hybrid fire test of a concrete-filled steel tube (CFST) column using an advanced HFT framework developed in previous research. A three-story, four-bay structure with the steel moment-resisting frame was selected for the validation. One column of the structure was physically represented in the laboratory, while the remainder of the structure was modelled numerically through finite element software. The physical specimen was heated following a standard fire curve. The experimental results are compared with numerical predictions and fire resistance tests of a similar single column to validate the performance of the developed method in full-scale applications. This comparison also provides insight into the performance of the column when acting as part of the larger structural system. The test results confirmed the proposed method can accurately simulate the complicated behaviour of a CFST column at high temperatures and subsequent failure. • HFT provides realistic, cost-effective fire safety insights compared to standard methods. • Tested CFST column experienced 80 % load increase during the HFT, no failure after 120 min. • Residual column strength was 3840 kN. • Load redistribution led to zero column force 40 min after the fire was stopped. • HFT closely matched numerical predictions, validating the hybrid testing framework. Abstract.