A Numerical Investigation of High-Strength Steel H-SA700 of Protected Beam with Cavity Under Elevated Temperature Including Creep Behavior

High-strength steel has been extensively used in numerous structures or high-rise buildings because of its high strength, ductility, and weldability. However, high-strength steel structures are vulnerable to fire hazards, so the ability to predict structural behavior is crucial in structural fire safety design. Creep behavior is one of the primary factors influencing the response of steel at high temperatures. This paper presents numerical studies using the fire dynamics simulator (FDS) and finite element method (FEM) coupling models to predict the structural behavior of a protected beam with a cavity for H-SA700 high-strength steel at elevated temperatures, including the creep effect. A comparison between simulation and experiment results demonstrates the validity of the process. In detail, based on a set of tensile tests conducted at six constant temperatures between 23°C and 600°C, the creep model is proposed. Subsequently, because creep is temperature-dependent, the heat transfer model used to predict the temperature distribution of the steel is developed. The effect of the partially damaged protection cover is discussed. Finally, it is found that with the temperature distribution from FDS-FEM integration and the proposed creep models, the collapse time of the beam can be defined. This study provides a practical approach for developing the creep model without creep tests and applying it to complex structures during fires.