Structural fire performance of RC beams via direct coupled temperature-displacement nonlinear simulation

This research demonstrates the utility of the Direct Coupling Technique (DCT) for capturing the intricate, dynamic interplay between thermal and structural responses, particularly when fire induces significant geometric changes. Implemented in ABAQUS, the DCT integrates thermal and structural analyses, solving for temperature and displacement fields simultaneously. It incorporates critical material properties, including thermal conductivity, specific heat, density, stress-strain behavior, and thermal expansion, to model the performance of RC beams across heating, cooling, and post-fire phases. Validated against experimental data from two beams, one that failed during a fire and the other assessed for residual capacity, the approach proves highly accurate. Furthermore, validation of experimental data on an intumescent-coated steel substrate was conducted to demonstrate DCT's ability to capture the thermal-mechanical response for significant deformation problems, with an error of 3.4 % compared to 127.3 % for the Sequential Coupling Technique (SCT) model. A detailed parametric study further explores key factors, including concrete cover, lateral stiffness, and compressive strength, providing insights to optimize RC beams against fire hazards. The DCT application facilitates a deeper understanding of fire-structure interactions and lays the groundwork for practical design tools, thereby potentially enhancing structural safety and efficiency.