BEHAVIOR OF CONCRETE UNDER FIRE EXPOSURE

Abstract

Service structures could be built from different materials and concrete is commonly used in construction due to its beneficial mechanical properties, such as its superior compressive strength, long-lasting durability, and ability to resist fire. Structures are anticipated to withstand the various loads they encounter during their operational lifespan, which can typically be determined based on factors such as the type of service, geographical location, and dimensions. These loads can be accurately modeled using advanced software tools that are continuously evolving. However, fire incidents are difficult to predict, making it challenging to foresee their location, timing, and the extent of their impact on structures, resulting reductions in strength and unexpected stress. Therefore, in this study, to examine the performance of concrete of different strength grades and reinforced concrete (RC) beam specimens exposed to fire at different temperatures, an experimental investigation was carried out. During the test, the maximum duration of fire exposure taken is four hours and maximum concrete surface temperature considered is limited to 246°C. For the RC beams, test was conducted under onepoint loading with different specimens of 25 mm and 35 mm concrete covers. The results showed that, the strength of RC beam after fire exposure reduces up to 18% and the compression strength of concrete at 246°C of fire exposure temperature with 25 MPa and 30 MPa were observed to drop by 32%, and 48%, respectively as compared to initial strength. Moreover, comparison of experimental results with numerical models were made. The results revealed that the predicted values of the residual compressive strength proposed by Hertz's model are in good agreement with the experimental values.

Keywords

• rc beam
• residual strength
• fire exposure
• temperature