火灾中植筋试件极限承载力试验研究

Experimental study on ultimate strength of post-installed rebar subjected to fire

为研究火灾下植筋试件极限承载力与受火时间的关系,进行了火灾下4个植筋试件拉拔试验.采用自制试验炉对植筋试件受火升温,当到达设定时间后,进行拉拔试验,试验中记录植筋试件的拉拔力,植筋末端位移及受火时间.试验结果表明:在受火时间不超过30 min时,15d和20d(d为钢筋直径)植筋试件的极限承载力降低程度不同,但当受火时间大于45 min后,两者的极限承载力相差不大.当受火时间超过60 min后,两种不同植筋深度植筋试件的极限承载力下降约85%.15d植筋试件和20d植筋试件分别在受火时间不超过15 min和30 min时可以保证钢筋屈服.

To study the relationship between ultimate strength of post-installed rebar and fire duration,4 specimens in fire were designed and tested.The test procedure included specimen installation,heating by oil burner and testing when the heating time reached to the fixed time.Records had been made on the temperature,the ultimate strength,the rebar displacement and the heating time.The test results show that when the fire duration is less than 30 min,the ultimate strength of 15d have great difference from that of 20d.While the fire duration is more than 45 min,the ultimate strengths of 15d and 20d have little difference from each other.When the fire duration is more than 60 min,the ultimate strength at high temperature decreases about 85% of that at ambient temperature.The post-installed rebar can yield when the fire duration for 15d or 20d specimen is less than 15 min or 30 min,respectively.