Akkannavar, C.S.Prashanth, M.H.2026-02-032025Journal of Structural Fire Engineering, 2025, 16, 2, pp. 200-21620402317https://doi.org/10.1108/JSFE-05-2024-0013https://idr.nitk.ac.in/handle/123456789/20270Purpose: In structural fire engineering, the design of columns is done either by prescriptive approaches or by empirical equations derived from experimental research. Performance-based design is the emerging methodology for designing structures under fire, which is case-specific. There is a need to develop design equations from first principles to design/find the residual strength of the column at elevated temperatures. The present study aims to develop equations from stress block parameters to find the residual strength of reinforced concrete (RC) columns subjected to elevated temperatures. Design/methodology/approach: The stress-strain variation across the cross-section of the RC column is determined at elevated temperatures. Based on the updated stress distribution diagram, stress block parameters are derived for various depths of neutral axis (NA) and different temperatures. Using updated stress block parameters, Pu-Mu interaction curves are generated for elevated temperatures. The results are verified against conventional methods and experimental results. Findings: The load-carrying capacity calculated from the proposed methodology is analogous to the experimental results. The methodology can be utilized to estimate the residual strength of RC columns subjected to elevated temperatures. Originality/value: The work done here attempts to develop the equations to estimate the residual strength of the column. The work involves calculating the strength of columns subjected to fire curves. © 2024, Emerald Publishing Limited.Columns (structural)Concrete blocksDesign of experimentsLoad limitsPressure vesselsResidual stressesStress-strain curvesStructural dynamicsDesign MethodologyElevated temperatureFire design methodologyFire designsInteraction diagramReinforced concrete columnResidual strengthStress block parametersTemperature dependentTemperature-dependent stress block parameterFires