冷成型钢复合墙体高荷载比率抗火试验研究

Fire Experiments of Cold-Formed Steel Walls Under High Load Ratios

已有的冷成型钢复合墙体抗火试验大多针对低荷载比率,其试验结果并不能反映该类墙体在高荷载比率作用下的抗火性能。设计制作了两片不同保温构造的足尺冷成型钢复合墙体模型,开展了其高荷载比率(荷载比率为0.85)抗火试验研究。结果表明高荷载比率作用下,墙体破坏模式发生改变,由低荷载比率作用下龙骨热翼缘的局部屈曲变为龙骨立柱全截面压屈。双层石膏板覆面板材墙体试件W1的耐火极限仅为37 min,龙骨立柱在柱底区域发生全截面压屈破坏;试件W2在龙骨空腔中加入了SAP保温材料,且采用蒸压轻质混凝土板、玻特板作为覆面墙板,其耐火极限达到了200 min,龙骨破坏模式不变但破坏位置由龙骨底部转移至龙骨顶部,原因是火灾环境下,龙骨上部空腔中的SAP保温材料最先完全脱水,造成龙骨上部的温度迅速升高且材性快速退化。

The fire experiments of cold-formed steel(CFS) walls are mostly conducted under a low load ratio, and the experiment results can not reflect the fire resistance of the wall under the action of high load ratios.In this paper, two full-scale CFS walls with different thermal insulation structures are designed and manufactured.The fire experiments of high load ratio(0.85 load ratio) is carried out.The results show that the failure mode changes under the action of high load ratio, and the local buckling of the hot flange of stud becomes a full section buckling of the stud column under the action of low load ratio.The fire resistance limit of W1 of double layer gypsum plaster board coated panel wall is only 37 min, and the full section compression and bending failure of stud occurs in the column bottom area.The super absorbent polymer(SAP) insulation material is added to the stud cavity of the specimen W2,and the autoclaved lightweight concrete board and calcium-silicate board are used as cladding wall boards.The fire resistance limit of W2 reached 200 min.The failure mode of the stud is unchanged, but the damage position move from the bottom of the stud to the top of the stud, because under the fire environment, the SAP insulation material in the upper cavity of the stud is first completely dehydrated.The temperature of the upper part of the stud increases rapidly and the material properties degenerate rapidly.