火灾中植筋连接构件的抗火性能试验研究

为研究火灾中植筋连接构件的抗火性能,进行了35个化学植筋试件在不同温度下(25～200°C)的拉拔试验以及12个植筋连接混凝土构件的受火试验。拉拔试验重点研究了植筋胶的粘结力随温度变化的规律,以及不同温度下植筋胶的粘结—滑移关系,结果表明:随着温度升高,植筋胶的粘结力显著下降。植筋构件的受火试验中,考虑了植筋深度(15d,20d,d为钢筋直径)和保护层厚度(25、40、60mm)两种影响因素。首先对6个试件按ISO834标准升温曲线升温(荷载为常温下植筋构件设计承载力的10%),到指定时间后,加载至构件破坏失效,结果表明:植筋深度和保护层厚度对火灾中植筋连接构件的极限承载力均有重要影响。其后进行了6个构件的恒载升温试验(荷载为常温下常规植筋构件设计承载力的80%),直至构件破坏,结果表明:当保护层厚度小于40mm时,植筋深度和保护层厚度对耐火极限均有重要影响;当保护层厚度大于40mm时,对耐火极限的影响植筋深度要大于保护层厚度。

Experimental Study on the Anti-fire Performance of Post-Installed Rebar Connection Members in a Fire

To study the anti-fire performance of post-installed rebar anchorage system,the pull-out test is carried out on 35 steel pipe specimens at elevated temperature(25°C～200°C) and the fire test is conducted on 12 bonded rebar connection members.The pull-out test study focuses on the relationship of adhesive strength and temperature and bond-slip relationships of adhesive at high temperatures,which indicates that the bond strength of structural adhesives decreases remarkably with the increase of temperature.In fire endurance test and ultimate strength test,3 coverage thicknesses and 2 embedment depths are considerated.In the ultimate strength test,6 specimens are subjected to the ISO834 fire for a specified time with a constant load,which is set to be 10 percent of the design loading capacity of the same specimens at ambient temperature,and then the load increases till the specimens fail.The test results show that both coverage coat and embedment depth have significant effects on the ultimate strength of post-installed rebar connection members in the fire.In the fire endurance test,6 specimens are subjected to the ISO834 fire till the specimens fail with a constant load,which is set to 80 percent of the design loading capacity of the same specimens at ambient temperature.The test results indicate that both coverage thickness and embedment depth have significant effect on the fire resistance when the coverage thickness is less than 40mm;the embedment depth plays more important role when the coverage thickness is more than 40 mm.