Thermal and mechanical properties of high-strength structural steel HSA800 at elevated temperatures

• Thermal and mechanical properties of 800 MPa high strength steel were evaluated.
• Thermal conductivity, specific heat and thermal expansion data were also obtained.
• High-temperature mechanical property was obtained from steady-state tensile test.
• Test data were compared with previous test results, design codes and manuals.
• Predictive equations of high strength steel were proposed at elevated temperatures.

The temperature dependent material properties of structural steel are important for fire resistant (FR) design and fire simulation of steel structures. In this study, the material tests were conducted for a high-strength steel developed in Korea, namely HSA800, to determine thermal and mechanical properties at elevated temperatures up to 1000 °C. Then test results were compared with current design models – ASCE, Eurocode 3 and AISC to verify which design models are fit well to the HSA800 at the elevated temperature. The thermal properties test results show that the specific heat and thermal strain at elevated temperatures agreed well with those predicted by current design models but thermal conductivity was slightly less than the design models. In the mechanical properties test results, the ASCE model was adequate for predicting yield strength of HSA800. Eurocode 3 and AISC models were unconservative for predicting yield strength but conservative for elastic moduli. The stress–strain relationships of HSA800 at elevated temperatures were developed using Ramberg–Osgood model and they agreed well with the test results up to 2% strain.