Experimental Research On Shear Behavior Of Reinforced Concrete Beams Repaired By PVA-ECC

Engineering fiber reinforced Cementitious Composites(ECC)is getting more and more attention in repairing engineering because of its super toughness and excellent tensile crack resistance.The use of ECC in structural repair can achieve the effect of controlling crack growth and improving bearing capacity.It has the advantages of good durability,convenient construction and wide range of application.However,at present,ECC repair of existing reinforced concrete structure is mainly focused on the experimental study of flexural performance,the experimental study of shear performance is relatively less.Based on the three-point bending test,this paper mainly analyzes failure mode,crack width,load midspan deflection curve,stirrup strain,characteristic load and so on through the experimental study of three contrast beams and nine repaired beams.The results show that the rigidity of repaired beams is significantly raised,the deflection and stirrup strain lag behind the contrast beams,the crack shape is more serried,and the shear resistance is obviously improved;the characteristic load of repaired beam is markedly increased,and the corresponding load has increased most obviously when the first diagonal crack occurs in the test beam;The shear capacity of the test beam increases respectively with the decrease of the shear span ratio,the increase of the thickness of the repair layer and the decrease of the damage degree;the larger shear span ratio and the thickness of the repair layer are easy to cause the change of the failure form of the test beam.Based on the "truss-arch" theoretical model,considering the influence of three factors(shear span ratio,thickness of ECC repair layer and damage degree of existing reinforced concrete beam)on the shear performance of ECC repair concrete beam,the calculation formula of shear capacity of the ECC repair reinforced concrete beam is obtained,and the calculation value of the formula is in good agreement with the test value,which can provide reference for the repair engineering to a certain extent.