蠕变模型对约束钢梁抗火性能分析的影响

摘要

Significant creep deformation occurs in steel subjected to elevated temperatures and loading,and thus affects the deformation and load capacity of steel Structures in fire.Currently there are many creep models,which are not widely suitable.Significant effect on fire resistance analysis of steel beam can be observed using different creep models.In order to quantity this effect,comparison was made to analyze five kinds of creep model.Fire resistance of restrained beam under five creep models was analyzed using computer program and the results were compared with test data.Norton creep model revealed best agreement with test data.Finally,parametric study was conducted on the parameters affecting the fire resistance of restrained steel beams.It is showed that Harmathy creep model had a greatest effect on fire response of restrained steel beams.The degree of creep influence to fire resistance of restrained steel beams for different creep models under different load ratio and restraint were different.%钢材在高温和荷载作用下产生明显蠕变变形，影响火灾中结构的变形和受力性能。现有的蠕变模型较多，但没有一个广泛适用的蠕变模型。不同的蠕变模型对钢结构抗火分析结果有很大影响。为了量化蠕变模型对约束钢梁抗火性能分析的影响，对5种常用的蠕变模型进行了对比分析。采用编写的约束钢梁计算程序，分别计算5种蠕变模型下约束钢梁的抗火性能并与试验数据进行对比。结果表明，采用 Norton 蠕变模型的计算结果与试验数据吻合最好。最后对影响约束钢梁抗火性能参数进行了研究，研究发现，Harmathy 蠕变模型对约束梁抗火性能分析结果影响最大；不同蠕变模型对不同荷载比、约束刚度下的约束钢梁抗火性能影响程度均不同。