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To enhance the fire resistance of traditional timber structures， this study systematically investigates the fire evolution behavior， charring characteristics， and residual load-bearing capacity of full-scale Qing-style Five-Step Dou-gong brackets protected with a transparent fire-retardant coating. Experiments were conducted using an ISO 9705 standard fire test platform in conjunction with a TAW–2000 multi-functional mechanical testing system. The results demonstrate that the application of the transparent fire-retardant coating significantly improves the fire performance of the Dou-gong components. Specifically， the coating delayed the initial ignition time by 60 s and reduced the peak flame height and peak heat release rate by 15.8% and 23.0%， respectively， compared to unprotected brackets. During combustion， the coating facilitated the formation of a dense， expanded char layer on the wood surface， effectively inhibiting heat and mass transfer， thereby controlling the charring process and minimizing mass loss. For instance， the most severely damaged component， the Zhengxin Guagong， exhibited reductions in charring depth and mass loss rate of 31.9% and 11.1%， respectively. Components oriented along the Qiaotou direction， which experienced weaker heat feedback， demonstrated even more pronounced improvements， with charring depth reduction rates exceeding 54.0%. Post-fire mechanical tests revealed that the protected Dou-gong brackets retained superior load-bearing capacity， with the maximum residual load increasing from 32.4 kN to 49.6 kN and the corresponding axial displacement rising from 47.6 mm to 82.3 mm. The load-displacement curve of the protected specimens was smoother and more stable， indicating improved structural integrity and resistance to fire-induced damage. In conclusion， the transparent fire-retardant coating not only effectively retards the combustion process and mitigates thermal degradation but also significantly enhances the post-fire mechanical performance of Dou-gong brackets. This provides a reliable technical approach for the fire protection of valuable historic timber structures. The findings offer crucial experimental data and theoretical support for performance-based fire safety design and the conservation of ancient wooden buildings.
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Basic Information:
DOI：10.13637/j.issn.1009-6094.2025.2010
China Classification Code:TU352.5
Citation Information:
[1]Yan Long,Zhao Zhijing,Gong Chenfei ,et al.Fire evolution characteristics and residual load-bearing capacity of Qing-style Five-Step Dou-gong brackets treated with transparent fire-retardant coatings[J].Journal of Safety and Environment().DOI:10.13637/j.issn.1009-6094.2025.2010.
Fund Information:
国家自然科学基金项目（52276143，52576152）; 湖南省科技计划项目（2025RC3039）
2026-07-20
2026-07-20
2026-07-20