增强约束拼合式轻型钢-混凝土组合柱抗火性能试验研究

Experimental study on fire resistance of reinforced restrained light steel-concrete composite columns

针对目前低层冷弯薄壁型钢房屋抗火性能较弱的特点,提出了一种应用于冷弯薄壁型钢承重结构体系的增强约束拼合式轻型钢-混凝土组合柱(以下简称“增强约束组合柱”)。通过对4个增强约束组合柱进行标准升温条件下的耐火性能试验,得到各组合柱的轴向位移、侧向位移、测点温度、耐火极限及破坏模式。建立了增强约束组合柱抗火分析模型,采用试验数据对模型进行了验证,进而对影响增强约束组合柱耐火性能的因素进行参数分析。结果表明:荷载比对增强约束组合柱耐火极限影响较大,荷载比越小,耐火极限越大,当荷载比取0.3~0.7时,组合柱耐火极限范围为30~105 min;具有增强约束作用的内置钢筋笼对提高组合柱耐火极限也有显著效果,增幅为69%;组合柱耐火极限随其截面尺寸增大而提高,随着铆钉间距增大而降低;对于采用铆钉的拼合截面,建议铆钉间距不宜大于100 mm。

In view of the weak fire resistance of low-rise cold-formed thin-walled steel buildings,a reinforced and restrained light steel-concrete composite column(hereafter referred to as‘reinforced and restrained composite column’)was proposed for the cold-formed thin-walled wall system.In this study,fire resistance tests of four reinforced and restrained composite column specimens subjected to standard elevated temperature conditions were carried out.The axial displacement,lateral displacement,temperature of measuring points,fire resistance limit and failure mode of each specimen were obtained.The fire resistance analysis model of reinforced and restrained composite columns was established.The model was verified against the experimental data,and then based on the model,the factors affecting the fire resistance of reinforced and restrained composite columns were analyzed.The results show that the load ratio has a great influence on the fire resistance of reinforced and restrained composite columns,the smaller the load ratio,the greater the fire resistance.When the load ratio is 0.3-0.7,the corresponding fire resistance of the specimen is 30-105 min.The built-in steel cage used for strengthening restraint also has a significant effect on improving the fire resistance limit of the specimen,and the increase ratio is up to 69%.The fire resistance limit of members increases with the increase of sectional size and decreases with the increase of rivet spacing.The rivet spacing is suggested to be less than 100mm.