采用蠕变试验机对低合金Q345钢进行高温蠕变试验,得到高温下的蠕变曲线。基于试验数据和现有蠕变模型,拟合得到Q345钢复合时间强化蠕变模型和Norton蠕变模型。利用蠕变模型对Q345钢柱的抗火性能进行分析,得到高温下Q345轴压钢柱承载力与受火时间关系曲线以及ISO 834标准升温条件下钢柱的荷载比和临界温度的关系。研究表明:Q345钢在700~800℃断裂前蠕变变形达到最大值;考虑蠕变后钢柱受火初期的承载力随受火时间的延长急剧降低,随后趋于稳定;ISO 834标准升温条件下,荷载比在0.2~0.8内考虑蠕变后钢柱的失效临界温度降低60℃左右。 Creep testing machine for low alloy Q345 steel creep test at high temperature, the creep curve at high temperature. Based on the experimental data and the existing creep model, the Q345 composite time-hardening creep model and the Norton creep model were obtained. The creep model was used to analyze the fire resistance of Q345 steel column. The relationship between the bearing capacity of Q345 steel column under high temperature and the fire time and the load ratio and critical temperature of steel column under the ISO 834 standard temperature rise were obtained. The results show that the creep deformation of Q345 steel reaches the maximum value before 700 ~ 800 ℃ fracture, and the bearing capacity of steel post-quenching decreases sharply with the prolongation of fire time after creep, and then tends to be stable. The temperature rise of ISO 834 Under the load ratio of 0.2 ~ 0.8, consider the failure of the steel column creep lower critical temperature of about 60 ℃.