Effects of Compressive Strength of Concrete on RC Columns Subjected to Elevated Temperatures

Fire is a significant threat to structural integrity. Depending on the structure architecture, intensity and duration of fire, beams and columns may lose strength and stiffness leading to collapse either by flexural failure, buckling or crushing. This paper focuses on the effect of elevated temperature on M 20 grade, M 45 grade and M 60 grade columns. The variation in axial capacity, lateral deformation and failure modes upon exposure to elevated temperatures were studied. It was observed that the grade of concrete has a significant effect on the strength of columns at different temperatures. When the grade of concrete is increased from M 20 to M 60, the strength of columns is decreased by 46%, at 400 °C. The models developed from the experiments have been compared with those predicted by the IS, British, American and Eurocode for RC compression members and presented. Simplified interaction curves to predict the strength of columns with different grades of concrete, subjected to axial load after exposing them to elevated temperatures, are developed.