Study On The Interface Behavior Of CFRP-High Strength Concrete Under Freeze-Thaw Cycles

In the northern coastal areas, freeze-thaw cycles is one of the greatest threat to the durability of concrete structures. In recent years, high-strength concrete has been very widely used because of its high strength and good corrosion resistance. However, due to the design and construction reasons, many concrete structures are faced with the problem of reinforcement. So it is very important to take economical and effective means of reinforcement when problems arise in concrete structure. Thus, reinforcement technology of high-strength concrete structure is known as an important topic of current research. CFRP is widely used in the field of concrete structure reinforcement because of its advantage like high strength, low density, good corrosion resistance, low cost and easy construction, etc.Based on the above application background, CFRP-high strength concrete double shear test was conducted under freeze-thaw cycles in this paper according to the National Natural Science Foundation of China, "Durability Study of FRP-High Strength Concrete subjected to Hold Lodes in Complex Marine Environment" (51378090). Two finite element numerical models were established to study the changes in the interface properties under freeze-thaw cycles. The contents and conclusions are as follows:Firstly, quick freezing method was used to examine performance of CFRP-high strength concrete under freeze-thaw cycles. The results indicate that freeze-thaw cycles will reduce the ultimate bearing capacity, the inter-facial energy and the maximum local shear stress; Softening stage become more and more inconspicuous when the freeze-thaw cycles increase; Failure mode is concrete surface stripping.Then established a cohesive finite element numerical model based on the interface test parameters to compare and discusse with the experimental results. The results find that finite element modeling and experimental results are in good agreement and ultimate end displacement decrease as the number of freeze-thaw cycles increase.Finally, a finite element modeling based on concrete plasticity damage model was established and compared with cohesive element model and experimental results. This method simulated the effects on concrete caused by freeze-thaw cycles by changing the concrete plastic damage model. Results indicate that the freeze-thaw cycles cause a small increase in the effective bond length, deepen the depth of concrete damage and reduce ultimate end displacement. The numerical model and the experimental data are in good agreement,so this model is recommended as a predictive model of CFRP-high strength concrete under freeze-thaw cycles.