CFD-Based Fire Risk Assessment and Control at the Historic Dong Wind and Rain Bridges in the Western Hunan Region: The Case of Huilong Bridge

Abstract

The Dong wind and rain bridges in western Hunan are among the most extraordinary historical buildings that express the unique culture of the Dong people, and are an unparalleled display of history, culture, aesthetics and architectural skills, but they are exposed to various disasters. However, fire poses a serious challenge to historical wind and rain bridges. This study investigated the fire risk of wind and rain bridges in terms of building materials, structural forms, fire habits, and fire loads. Fire dynamics simulator software and SketchUp modeling software were used to visualize and numerically simulate fire conditions. The survey results indicated that the fire load of the Huilong bridge was 1,794,561 MJ. After a fire, the central pavilion underwent a flashover at 200 s. By 600 s, the maximum temperature of the bridge was 1200 °C, and the entire bridge was in flashover condition. Furthermore, targeted fire-mitigation strategies were proposed according to the architectural characteristics and cultural environment of the wind and rain bridges in terms of the following four components: automatic fire-extinguishing equipment, fireproof coatings, suspended ceiling, and skylights. The effectiveness of the fire-resistance performance of the strategies was also evaluated. The fireproof coating measures were the most effective, and the bridge sections delayed reaching the flashover state by 40–80 s. The reported results can help reduce the fire-related risks of wind and rain bridges and protect our historical heritage more effectively and efficiently. Furthermore, this study can serve as a reference for other historic wooden structures to develop appropriate mitigation strategies.