盐腐蚀环境下内嵌FRP筋加固混凝土界面黏结性能试验研究

Experimental study on interface bond behavior of concrete strengthened with NSM FRP bars under salt corrosion environment

为了研究盐腐蚀环境下内嵌FRP筋加固混凝土界面的黏结性能,对27个内嵌FRP筋加固混凝土试件进行盐腐蚀后的单端拉拔试验,分析试件的受力过程和破坏模式,研究内嵌FRP筋黏结长度、腐蚀时间和FRP筋类型对界面黏结性能的影响。结果表明:盐腐蚀的试件破坏模式分为结构胶劈裂、FRP筋拉断和结构胶劈裂且FRP筋弯折等3种,且以结构胶劈裂破坏为主。盐腐蚀环境下内嵌FRP筋混凝土试件的黏结应力与黏结长度、破坏模式与腐蚀时间有关。盐腐蚀环境会影响混凝土、黏结材料及FRP筋的力学性能,加剧黏结界面失效破坏。腐蚀时间为30 d和90 d的内嵌BFRP筋加固混凝土试件的耐盐腐蚀能力高于内嵌GFRP筋加固混凝土试件的,腐蚀时间为60 d的内嵌GFRP筋加固混凝土试件的耐盐腐蚀能力优于内嵌BFRP筋试件的。根据试验数据拟合了盐腐蚀环境下内嵌FRP筋加固混凝土界面黏结-滑移本构关系,其拟合优度达到0.9880。

The pull-out tests of 27 concrete specimens strengthened with near-surface mounted(NSM)fiber reinforced polymer(FRP)bars were carried out to investigate the interface bond behavior of specimens under salt corrosion environment.The bearing process and failure modes of the specimens were analyzed.The effects of the bond length of FRP bars,corrosion time and type of FRP bars on the interface bond behavior were studied.The results show that the failure modes of the specimens under salt corrosion are divided into three types,including adhesive epoxy splitting,the rupture of FRP bars and adhesive expoxy splitting accompanying FRP bars bending,and the main failure mode is adhesive epoxy splitting.The bond stress of specimens in salt corrosion environment is related to the bond length,failure mode and corrosion time.The mechanical properties of concrete,adhesive materials and FRP bars can be affected by salt corrosion environment,which aggravates the interface bond failure.The salt-corrosion resistance of concrete specimens strengthened with NSM basalt fiber reinforced polymer(BFRP)bars in corrosion time of 30 days and 90 days is greater than that of concrete specimens strengthened with NSM glass fiber reinforced polymer(GFRP)bars.The salt-corrosion resistance of concrete specimens strengthened with NSM GFRP bars in corrosion time of 60 days is better than that of specimens strengthened with NSM BFRP bars.According to the test data,the constitutive relationship of the bond-slip between the embedded FRP bars and the concrete interface was fitted under salt corrosion environment,and the goodness of fit reaches 0.9880.