快速荷载下CFRP-高温后混凝土界面正拉粘结性能试验

EXPERIMENTAL STUDY ON INTERFACIAL TENSILE BONDING PERFORMANCE OF PRE-HEATED CFRP-CONCRETE UNDER FAST LOAD

该文通过对90个CFRP-高温后混凝土标准试件进行快速荷载下正拉试验,得到了加载速率、混凝土强度等级及过火温度等因素对界面正拉粘结强度的影响规律。在欧洲规范(CEB-FIP1990)建议的混凝土动态抗拉强度公式和高温后混凝土轴心抗拉强度折减公式基础上,综合考虑应变率效应和高温劣化作用,提出了高温后界面正拉粘结强度预测模型,并验证其可靠性。在此基础上给出了不同混凝土强度等级构件火灾后极限加固修复温度。试验结果表明:正拉粘结强度随混凝土强度等级和加载速率的提高而提高;在20℃~500℃内提高过火温度会显著降低界面正拉粘结强度,超过500℃后下降幅度不明显。

Tensile tests of 90 pre-heated CFRP-concrete specimens were conducted under fast load. The influences of three critical parameters on tensile bonding strength were investigated, including loading rate, concrete strength and heating temperature. According to the formula for dynamic tensile strength of concrete suggested by European code CEB-FIP1990 and the formula for the reduced axial tensile strength of concrete after elevated temperature, a model for estimating the interfacial tension bonding strength after elevated temperature was developed and verified. The limit temperature for repair and rehabilitation of concrete component after fire was suggested in terms of different strength grades to concrete. Results show that the tensile bonding strength increases with the increase of loading rate and concrete strength. In the range of 20 ℃ to 500 ℃, the interfacial tensile bonding strength significantly decreases with the increasing heating temperature, but no remarkable decrease is observed over 500 ℃.