高强度Q690钢柱耐火性能试验研究

为了获得高强度Q690钢柱的耐火性能,使用电炉对无防护足尺焊接H形Q690钢柱进行模拟ISO834升温条件下耐火试验.测量得到不同荷载比下Q690钢柱温度、轴向位移、侧向位移与受火时间的关系,基于试验数据得到钢柱的临界温度和耐火极限.采用ABAQUS有限元软件建立钢柱耐火性能分析模型,考虑钢材高温蠕变和焊接残余应力的影响,模拟得到了钢柱的受火响应,其与试验结果吻合良好.利用验证的有限元模型分析了荷载比、长细比和升温速率对钢柱受力性能的影响.研究表明,无防护的Q690钢柱在受火20min左右发生破坏,破坏模式为整体失稳破坏;荷载比对临界温度影响较大,长细比和升温速率影响较小;Q690钢柱的临界温度比GB51249-2017《建筑钢结构防火技术规范》和欧洲规范EN1993-1-2的计算结果低60℃左右.最后提出了高强Q690钢柱抗火设计的简化方法.

Experimental study on fire resistance of high strength Q690 steel columns

To obtain fire resistance capacity of high strength Q690 steel columns, fire tests on full-scale H-shaped welded Q690 steel columns were carried out by using furnace subjected to ISO 834 fire curve. The relationships between temperature of Q690 column, axial displacement, lateral displacement and fire duration were measured under different load ratio. Critical temperature and limited fire resistance were obtained based on the test data. Fire resistance analysis model was established by employing ABAQUS software by taking the effect of high temperature creep in steel and residual stresses variation into consideration. Fire response of steel columns were simulated and good agreement was found between simulation and test. The effect of load ratio, slenderness ratio and heating rate on mechanical behavior of steel columns were analyzed by the validated finite element model. The study shows that bear steel columns only survive about 20 min in fire and the failure mode is overall buckling. Load ratio has great influence on fire resistance of Q690 steel columns. However, slenderness ratio and heating rate have minor effect. The critical temperature of Q690 steel columns is about 60℃ lower than those predicted by Chinese code GB 51249—2017 and Eurocode EN 1993-1-2. Finally, a simple approach for fire resistance design of Q690 steel columns was proposed.