Open Access

ARTICLE

Thermo-Mechanical Behavior and Residual Strength of Reinforced Concrete Beams under Fire Exposure

Hongyan Liu, Fang Wang, Jie Zhao, Feng Wu^*

School of Architecture and Design, Yunnan Technology and Business University, Kunming, China

* Corresponding Author: Feng Wu. Email:

(This article belongs to the Special Issue: Advanced Strategies for Structural and Non-Structural Seismic Protection and Damage Prediction in Reinforced Concrete Structures)

Structural Durability & Health Monitoring 2026, 20(5), 13 https://doi.org/10.32604/sdhm.2026.079457

Received 21 January 2026; Accepted 22 April 2026; Issue published 24 August 2026

Abstract

This study investigates the thermo-mechanical behavior and residual strength of full-scale reinforced concrete (RC) beams subjected to ISO-834 fire exposure, emphasizing temperature-dependent material degradation and bond-slip effects. A sequentially coupled numerical framework was developed in ABAQUS, integrating a temperature-indexed Concrete Damage Plasticity (CDP) model for concrete, elastoplastic steel constitutive laws, and a temperature-dependent bond-slip model implemented via nonlinear SPRING2 elements. The model explicitly accounts for post-peak concrete softening, steel yield degradation, and interface deterioration, and was calibrated against full-scale experiments. Experimental measurements included internal and surface temperatures, load–midspan deflection, and residual strength after natural cooling. The numerical results closely reproduce the experimental observations, with deviations of 7%–10% for both mid-span deflection and ultimate load. Key findings include: C40 concrete retains ~60% of its ambient compressive strength at 300°C–400°C; stiffness and peak load decrease by 30%–70% and 40%–50% at 600°C, respectively; residual load capacity drops to 20%–25% at 700°C. Steel yield strength decreases by ~50% at 600°C, and bond deterioration accelerates deflection and reduces residual capacity. This integrated numerical–experimental framework provides a validated predictive tool for post-fire performance assessment of RC beams, supporting fire-resilient design and structural safety evaluation.

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Keywords

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