考虑蠕变的约束钢梁抗火性能分析方法

高温和荷载共同作用下钢材产生明显的蠕变变形,对钢结构在火灾下的变形和受力性能产生较大的影响。在约束钢梁抗火性能分析中考虑蠕变的影响,引入钢材的高温蠕变模型,通过考虑蠕变产生的钢梁截面应变,建立考虑钢材高温蠕变影响的约束钢梁分析理论,并利用MATAB编写了计算机程序。采用该程序计算了火灾下约束钢梁的约束轴力和跨中挠度,计算结果和试验数据吻合较好。采用验证后的程序进一步分析了蠕变对简支钢梁和约束钢梁抗火性能的影响。研究表明:提出的分析方法可以准确考虑蠕变对钢梁抗火性能的影响;蠕变效应对简支钢梁耐火极限影响较小,而对约束钢梁影响较大。

Approach to analysis fire resistance of restrained steel beams after considering creep effect

Significant creep deformation occurs on steel with the coaction of high temperature and loading, and the creep has a large effect on the deformation and load bearing capacity of steel beams in fire. In order to consider the effect of creep on the fire resistance performance of restrained steel beams, the high temperature creep model is employed to establish analysis theory on restrained steel beams by considering creep strain in the cross section of steel beam. And a computer program is performed by using MATLAB software. Restrained axial force and deflection of restrained beam under fire are analyzed by the computer program, and good agreement is found between calculation results and test data. The effect of creep on the fire resistance performance of simply supported beams and restrained steel beams is further investigated by employing the validated program. The results show that the proposed approach can accurately consider the effect of creep on the fire resistance performance of steel beams, and creep has a small effect on the fire resistant performance of simply supported beams, but has a large effect on that of restrained beams.