Investigation of Fire Effects on Reinforced Concrete Members via Finite Element Analysis

Abstract

Structural deterioration during fire leads to significant economic losses, severe injuries, and deaths. Research to accurately estimate the impact of fire on structural security and performance, and to identify ways to reduce it, has been increasing recently with capital investments in the building and infrastructure sectors. This research aims to establish a reliable algorithm for simulating the behavior of reinforced concrete (RC) beams under thermal and structural loads. The proposed algorithm is based on the combination of thermal and structural analyses using the sequential link technique. These analyses use material characteristics such as conductivity, specific heat, stress-strain relationship, and thermal expansion to capture thermal and structural responses during the heating phases according to Eurocode 1 and Eurocode 2 using the finite element method. Beam models in the study, which have been exposed to the ISO-834 fire curve, were designed to exhibit flexural failure. Nonlinear numerical analysis results have mostly coincided with the previous studies regarding the residual load-bearing capacity. Depending on the outcomes of the previous experimental studies, an RC member's structural strength increases when the internal temperature is between 150 and 250 °C and degradation starts after 300 °C. This outcome has been supported by the previous numerical and experimental studies, propounding the accuracy of preferred modeling and analysis approaches. As the essential distinctness of the research, the effects of elevated temperatures on the bonding behavior between concrete and rebar were considered for numerical analyses.