Mechanical Properties of Q345 Weathering Steel Exposed to High-Temperature After Air and Water Cooling

Weathering steel is a high-strength low alloy steel with a dense rust layer formed by alloying elements and corrosion resistance to prevent corrosion from spreading. In recent years, China has developed a new type of Q345 weathering steel (Q345WS). This study experimentally investigates the post-fire characteristics of Q345WS steel at temperatures ranging from 20 to 1000 ℃. The research analyzes the effects of air cooling and water cooling conditions on the steel, particularly focusing on residual strength post-fire. The study also compares the residual mechanical properties of Q345WS steel with those of other structural steels. When exposed to temperatures up to 600 ℃, the loss of mechanical properties could be negligible. The residual mechanical properties of Q345WS steel are significantly influenced by the high temperature and cooling method when the temperature exceeds 600 ℃. The variations in mechanical characteristics between Q345WS steel and construction steel under high temperatures should be highlighted, and comparable with findings from previous literature on various steel types. A series of polynomial prediction equations have been suggested to forecast the alterations in the mechanical attributes of Q345WS following exposure to fire, offering a methodical and conceptual foundation for assessing steel structures and carrying out post-fire retrofitting.