Mechanical properties and constitutive model of fire-resistant steel at elevated temperature
Year: 2025
Type: article
Abstract: Fire-resistant steel offers improved retention in strength and elastic modulus at high temperatures, enhancing the fire performance of steel structures. However, unified constitutive models for the high-temperature behavior of fire-resistant steel are still limited. This study aims to develop a broadly applicable high-temperature constitutive model based on experimental research and comparative analysis. Fifty high-temperature steady-state tensile tests were conducted on Q355FRC fire-resistant steel in accordance with Chinese and American testing standards, covering a temperature range from room temperature to 900 °C. The results show that Q355FRC fire-resistant steel does not exhibit a yield plateau at either room or elevated temperatures. Compared with conventional structural steel, Q355FRC fire-resistant steel shows improved high-temperature performance, retaining approximately 78 % of its elastic modulus and about two-thirds of its nominal yield strength even at 600 °C. The reduction coefficients specified in current design codes for conventional structural steel tend to be conservative for fire-resistant steel. To address this issue, predictive equations and a modified three-stage Ramberg–Osgood model are proposed. The generality of the proposed three-stage model is validated using experimental data from other studies. Simplified expressions for strain-hardening parameters are developed, enabling convenient estimation of the high-temperature mechanical properties for a broader range of fire-resistant steel grades.
Authors: Yun Cheng, Xianglin Yu, Yongjiu Shi, Yi Li
Institutions: Tsinghua University, Hong Kong Polytechnic University
Language: English
Subfield: Civil and Structural Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,310
Award: G632886293
OpenAlex ID: W4413105572