Analyzing Rebar Temperature in Fire-Damaged Reinforced Concrete Beams: Finite Element Validation and Simplified Method Comparison.

Abstract

This study focuses on analyzing the temperature distribution in fire-damaged reinforced concrete beams, utilizing both finite element analysis (FEA) and various simplified methods. The primary objective is to validate the temperature profiles obtained from experimental tests at different locations within the beams against FEA results and to compare these with predictions from simplified methods. The research identified that employing average conductivity values, an emissivity of 0.8, and a mesh size of 25mm in the FEA model yielded consistently accurate temperature predictions. Among the simplified methods evaluated, Wickstrom's method demonstrated the highest accuracy, with minimal error compared to FEA results, across different cover thicknesses and fire exposure durations. Kodur's method showed moderate Wickstrom's but lower than those of Desai. Desai's method had the largest discrepancies, making it the least reliable. Additionally, the study confirmed that increasing the concrete cover thickness decreases the temperature at the reinforcement bars (rebars), due to enhanced insulation provided by the additional concrete, which slows heat transfer from the fire-exposed surface to the rebars. This research provides valuable insights for improving the accuracy of temperature predictions in fire-exposed reinforced concrete beams, contributing to the development of more effective fire- resistant structural designs.