Simplified Method to Predict Residual Strength of Reinforced Concrete Columns Under Natural Fire Conditions

Abstract

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.