| Carbon Fiber Reinforced Plastic (CFRP) is widely applied to strengthened structuresand new CFRP concrete composite structure for its lightweight, high strength and elasticmodulus which is similar to the steel. The strengthened members have3failure models:crushing of concrete, abruption of CFRP and debonding failure of CFRP. In the debondingfailure model, the phenomenon of a thin layer of concrete is peeled off caused by theconcrete crack in the middle of beam which cases the stress concentrating of CFRP is morecommon. The debonding not only decreases the reinforcement effect, but also impacts thesafety of the structures. Most previous studies on debonding failure focus on macroscopicview. It is necessary to study form the microscopic scale for the purpose of analyzing theessence of structure failure.The paper study the mechanical properties of CFRP strengthened beam under thebending load, and explore the CFRP debonding from the microscopic scale firstly.3-Dfinite element model has been established and by ABAQUS and mechanical properties hasbeen analyzed. A beam segment was intercepted from the model, and the randomaggregate has been added to the3-D and2-D beam segment. Studying from microscopicscale, failure mechanism has been analyzed, and relevant suggestion has been given after.In the paper, the debonding of CFRP, which the crack is developing in the case whereCFRP reinforcement plain concrete notch beam under the shear force and bending momenthas been studied. XFEM has been used to simulate the developing of crack. The layer ofconcrete around CFRP is peeled off when the debonding happening has been simulated bycohesive element. Microscopic scale bond-slip constitutive is applied to the cohesiveelement. The study indicates: with the same beam height, the larger ratio of notched lengthto the height is, the less initial cracking load and ultimate load is; with the same ratio ofnotched length to the height, the higher beam height is, the larger initial cracking load andultimate load is. |
