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冷弯型钢高温下的力学性能是防火安全设计和数值分析的重要因素。现多采用稳态试验方法研究高温下材料的力学性能。然而,瞬态试验方法能更好地反应火灾的真实情况。采用瞬态和稳态两种方法对厚度为1mm的G550钢材进行试验,并对两种方法的试验结果进行讨论。结果显示,G550钢材的稳态试验结果不同于瞬态试验结果。G550钢材的稳态试验结果高估了冷弯型钢结构的耐火性。此外,将试验结果与其他研究人员的研究结果以及现有设计规范的计算结果进行比较,结果显示,采用BS5950计算的G550钢材屈服强度与瞬态试验结果相一致,比稳态试验结果保守。然而,其他情况下BS5950,AS4100和EC3的计算结果并不保守。最后,采用拟合法给出高温下考虑G550钢材的屈服强度、弹性模量、极限强度等折减因素的统一方程。基于Ramberg-Osgood模型给出G550钢材的应力-应变方程。该方程的计算结果与试验结果相符,能够满足实际工程的需要。
Mechanical properties of cold-formed steel at high temperatures are important factors in fire safety design and numerical analysis. Steady state test methods are often used to study the mechanical properties of materials at high temperature. However, the transient test method can better reflect the real situation of the fire. Two methods of transient and steady state were used to test G550 steel with a thickness of 1mm, and the results of the two methods were discussed. The results show that the steady state test results of G550 steel are different from the transient test results. The steady state test results of G550 steel overestimate the fire resistance of cold-formed steel structures. In addition, comparing the test results with the results of other researchers and the calculation results of existing design codes, the results show that the yield strength of G550 steel calculated by BS5950 is consistent with the transient test results and conservative with the steady state test results. However, the BS5950, AS4100 and EC3 calculations are not conservative in other cases. Finally, a uniform equation considering the yield strength, elastic modulus and ultimate strength of G550 steel under high temperature is given by using the fitting method. The Stress - Strain Equation of G550 Steel Based on Ramberg - Osgood Model. The calculation results of this equation are consistent with the experimental results, which can meet the needs of the actual project.