Faculty Publications
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Item Simplified Method to Predict Residual Strength of Reinforced Concrete Columns Under Natural Fire Conditions(Springer, 2024) Akkannavar, C.; Prashanth, M.H.; Joshi, C.Studies on the Reinforced Concrete (RC) columns under natural fire conditions are critical since the failure of columns leads to progressive failure of the building. Many experimental and analytical studies have been conducted to investigate the columns under fire conditions. Most studies have investigated fire conditions by utilizing standard time–temperature relationships such as ISO-834, ASTEM E119, and other nominal fire curves. This paper presents a simplified method to evaluate the axial capacity of RC columns subjected to natural or realistic fires. A parametric natural fire model is developed from EN.1991.1.2.2002 guidelines, considering important parameters into account to define the natural fire curve. Thermal analysis is carried out using the finite element software SAFIR to determine the temperature distribution within the column’s cross-section. The mechanical properties of concrete and steel change with an increase in temperature. The reduction factors for the compressive strength of concrete and the yield strength of steel at elevated temperatures are derived from Eurocodes. Using updated temperature-dependent strength parameters for concrete and steel, the capacity of a column is estimated. The proposed methodology can be used to estimate the residual strength of RC columns for realistic fire situations. © The Institution of Engineers (India) 2024.Item Residual strength estimation of RC columns subjected to elevated temperatures from stress block parameters(Emerald Publishing, 2025) Akkannavar, C.S.; Prashanth, M.H.Purpose: 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.