Mechanical properties of cold-formed high strength steel at elevated temperatures

This paper presents the mechanical properties of cold-formed high strength steel at elevated temperatures. Mechanical properties at elevated temperatures have a crucial role in fire resistance design of steel structures. The fire resistances of steel structures in the existing international standards are mainly based on experimental data of hot-rolled mild steel. However, investigation of high strength steel at elevated temperatures is limited. Therefore, a test program has been carried out to investigate the mechanical properties of cold-formed high strength steel at elevated temperatures. The coupon specimens were extracted from cold-formed high strength steel square and rectangular hollow sections with nominal yield stresses of 700 and 900 MPa at ambient temperature. The coupon tests were carried out through steady state test method for temperatures up to 1000 degrees C. Mechanical properties including elastic modulus, yield stress and ultimate strength were obtained from the tests. The test results were compared with the design values in the European, American, Australian and British standards. The comparison results revealed the necessity of proposing specified design rules for mechanical properties of cold-formed high strength steel at elevated temperatures.