Finite Element Analysis Of RC Beams Strengthened In Shear With Externally Bonded FRP Sheets Under Smaller Shear Span Ratio

Fiber Reinforced Polymer(FRP) are widely used in retrofitting/strengthening reinforced concrete(RC) structures due to its excellent performances, such as high strength-to-weight ratio, corrosion resistance and convenience for construction. The FRP composites has become an important material in the existing strengthening technology. It is an important research subject that FRP was applied into shear reinforcement of RC beams. In addition, the effect of shear span-to-effective depth ratio on shear performance is a very complex issue in FRP shearstrengthening RC beam. This paper analysis and summarize a large number of existing experiment researches and relevant finite element analysis of FRP shear-strengthening RC beam. For fixing this gap of the knowledge, This paper conduct the research on FRP shearstrengthening RC beams with smaller shear span ratio via the finite element analysis because it was rarely seen in current research.The shear span-to-effective depth ratio of the test beams this paper studied relatively are partial to be small, which are distributed at around 1.5. Among these test beams, containing two FRP reinforcement mode: externally bonded with U-wrapping FRP configuration and fullwrapping configuration. Besides, this paper also studied the RC beams and FRP shearstrengthening beams with stirrups or without stirrups respectively. Firstly, this paper built the finite element analysis model of RC beams, RC beams with U-wrapping FRP reinforcement and RC beam with full-wrapping reinforcement, based on concrete fracture energy theory and damage theory respectively, the above beams all contain stirrups. The prediction of these model on load-displacement curve, crack development and failure mode coincide with the experimental results. These models preliminary are verified as effective for FRP shearstrengthening RC beams with small shear span ratio. Then applying these models to the RC beam and RC beam with U-wrapping FRP reinforcement, these beams were published in literature and didn't contain stirrups. The numerical results are good agreement with experimental result as well. Thus, these models are verified again as effective and universally applicable for FRP shear-strengthening RC beams with relative small shear span ratio.This paper also analyzed the parameters which have great influence on finite element model, and get the conclusion that the model based on the rotated smeared crack model is suitable to simulating the cracking process and crack distribution, shear capacity of FRP shearstrengthening RC beams with small shear span ratio, however, the model based on the fixed smear crack model can't simulate accurately it. The mesh element shape also is a factor which has effect on shear capacity of beam. Besides, it is important to choose the proper bond interface when simulating the mechanical property of FRP-concrete interface. At last, this paper study the effect of the plastic displacement value which exist in compression of concrete constitutive on ultimate load state of beam.