Experimental Study On The Bond Behavior Between CFRP Composites And Concrete Under Impact Loading

In recent years, the CFRP reinforcement technology has been widely used instrengthening of existing reinforced concrete structure due to its high strength toweight ratio, excellent resistance to corrosion, easy to handle during construction andtransport and so forth. The interface mechanical characteristic between CFRP andconcrete determines the structural bearing capacity. But debonding is the major defectin structure strengthened by externally bonding, in which case the CFRP may notmake full use of the strength of materials. Therefore, the bond behavior betweenCFRP and concrete plays a critical role in a strengthening system with externallybonded CFRP. This paper presents a prelimnary study using a bending test method forexaming the bond behavior under static and impact loading, which provides thetheoretical and experimental research for design of concrete strengthened with CFRP.The main contents of this paper are summarized as follows:(1) Ten specimens with bonded CFRP sheets were tested under static load, thefailure modes under static load were analyzed. The distribution of strain, transmissionof interfacial stress and evolution of interfacial slip are discussed here. The four kindsof bond-slip constitutive relationship of CFRP-concrete interface are introduced, andthereafter the formulae for characteristic parameters of curves are also given here.(2) Eighteen specimens with bonded CFRP sheets were tested under impact loadby drop hammer, the failure modes under impact load were analyzed. The impactforce history curves and the interface capacity under impact loading were discussed.The transmission of interfacial stress, evolution of interfacial slip and the interfacialfracture energy are discussed here. The interface mechanical properties under impactload was compared with static load.(3) Numerical models of the static test and the impact test were established usinggeneral nonlinear FEA software ABAQUS, and the analysis result agreed with theexperimental result well. Meanwhile, it can provide a reference for the subsequentparameter analysis.