Finite Element Analysis On Shear Behavior Of FRP Shear-strengthened Beams With Stirrup Corrosion

Recently,Fiber Reinforced Polymer(FRP)has been widely used in the field of reinforcement,and the mechanical behavior of reinforced concrete(RC)beams shearstrengthened with externally bonded FRP is an important subject.The shear span-toeffective depth ratio and the stirrup corrosion are two important factors affecting the shear reinforcement of FRP.In order to study the coupling effect of shear span-toeffective depth ratio and stirrup corrosion on shear behavior of reinforced concrete beams,18 RC beams with different shear span-to-effective depth ratio(1,2 and 3),stirrup corrosion degree(0%,5% and 15%)and whether or not U-shaped FRP shear reinforcement are simulated by finite element analysis.The effect of stirrup corrosion on reinforced concrete beams is considered from three aspects: the deterioration of mechanical properties of stirrup,the change of bonding mechanical properties of stirrup-concrete interface and the deterioration of mechanical properties of concrete.Based on the fracture energy theory the crack band theory,the finite element model is established,and the following conclusions are drawn:(1)The conclusion that Both stirrup corrosion and shear span-to-effective depth ratio will affect the shear capacity of RC beams is verified by finite element analysis.When the stirrup corrosion degree is constant,the shear capacity decreases with the increase of span-to-effective depth ratio.When the span-to-effective depth ratio is constant,the shear capacity changes slightly in low stirrup corrosion degree.As the stirrup corrosion degree increases,the shear capacity decreases obviously.(2)Stirrup corrosion will change the bond-slip relationship of stirrup-concrete interface.The change has an effect on the maximum crack width,but has little effect on the shear capacity and the main crack pattern of reinforced concrete beams.(3)The simulation based on the fixed crack model is in good agreement with the test in the load-deflection curve and the main crack pattern,so the fixed crack model is suggested to establish the finite element model.In this paper,the element size effect has obvious influence on the beam with small span-to-effective depth ratio,but little influence on the beam with large span-to-effective depth ratio.The plastic displacement has a positive correlation with the ductility of the beam with small span-to-effective depth ratio,but has little effect on the beam with large span-to-effective depth ratio.(4)The load-deflection curve,the main crack pattern and the failure mode predicted by the finite element model are in good agreement with the experimental results,which verifies the validity and universality of the finite element model.In this paper,the three-dimension model and the model of concrete beams with various shear span-to-effective depth ratio are established,which verifies the validity and universality of the finite element model.What’s more,the parameter analysis of crack model,element size and plastic displacement,which has a great influence on the finite element model,is carried out.