国产Q345钢在不同热-力路径下的材料性能对比和材料模型应用

为评估和分析钢结构的耐火性能,以我国10个钢厂生产的Q345钢的424次恒载升温试验和152次恒温加载试验结果为依据,对钢材强度和应变以及不同的热-力作用路径下的力学性能进行对比研究。结果表明,在所有热-力作用路径下,恒载升温试验的强度最小,应变最大,临界温度最低;恒温加载试验的强度最大,应变最小,临界温度最高。随温度升高,热-力作用路径对钢材的力学性能影响增大:在450℃以下影响较小,在500℃以上时影响显著。如果规范采用恒温加载试验强度,是不可靠的。恒载升温条件下的ε-T-k材料模型和恒温加载条件下的ε-k-T材料模型均不能单独用于超静定钢结构的性能分析。超静定钢结构的性能分析可把火灾过程离散为若干时段,把每个时段分解为两个独立的应变-温度过程和应变-应力过程,分别应用恒载升温条件下的ε-T-k和恒温加载条件下的ε-k-T材料模型进行分析,然后迭加计算以得出最后的应变。

Comparison of mechanical behavior of 16Mn steel and application of material models under different stress-temperature paths

To evaluate fire resistance of steel structure,based on experimental research results of 424 times transient tests and 152 times steady state tests,strain-stress-temperature material model,model of total process modulus of elasticity under steady state tests and model of critical temperature under transient tests were established.Q345 steel specimens came from 10 factories in China.The mechanical behaviors of steel were compared under different stress-temperature paths.The results show that in all stress-te...