Fire-resistance design and experimental research for the stay cables of super-long span cable-stayed bridge

The cables are crucial to the service life of cable supported bridges. Fire accidents involving bridge cables may cause severe damage, impacting the structural integrity and performance of bridges, and therefore requires thorough attention and research. This research mainly focuses on the key technologies for the fire resistance of stay cables, including the structural system design of fire-resistant stay cables, selection of fireproof materials, and experimental verification of fire-resistant performance and qualification of the proposed system. The results show that the multiple wrapped composite structures with fire resistance are suitable for the fire-resistant design of stay cables in the Changtai Yangtze River Bridge. The fire-resistant structure of the stay cables is designed as one layer of flame barrier layer using 316L matte stainless steel, one layer of fire retardant layer using modified ceramic fiber cloth and two layers of insulation layer using aluminum foil glass fiber cloth. Moreover, the fire-resistant performance of the structural system is experimentally validated to meet the design requirements that the fire-resistant time of the stay cables should not be less than 60 min, and the temperature of the internal steel wire should not exceed 300 degrees C. Meanwhile, tensile testing under high temperature demonstrates that the designed stay cable can resist the applied load for 60 min under a high temperature of 300 degrees C at the surface of cable without slip or failure of anchorage components. The development of fireproof stay cable products, as applied in the Changtai Yangtze River Bridge project, provides a valuable reference for fire resistance design of bridge cables and contributes significant economic and social benefits.