Experimental Study Of Corroded RC Beams Strengthened For Shear And Flexural Resistance

Under the environment of chloride salt,chlorine ion may invade into the RC beam structure though a variety of ways,rusting away the steel bar by making use of the physical chemistry means,which descends the mechanical performance and lowers the adhesive capacity between reinforcement and concrete and causes concrete cracking,thus the carrying capacity of the structure and the character of service are insufficient,and the service life of the structure is shortened.Through the comparison of various strengthening methods,the method of bolting steel plates can be more effective to improve the bearing capacity of corroded damaged RC components.Selecting the form of flexural and shear strengthening of RC Beams can give fully play to the performance of steel plate and enhance the effect of reinforcement.After corrosion and reinforcement,structures are still subject to damage by chloride ion,that is to say it is a case of the secondary corrosion.Based on 12 pieces of corroded beams with different steel plates reinforcing methods,this paper investigate the influence of u-shaped hoop attached strip,steel plate,Concrete cover thickness and the secondary corrosion rate on the performance of reinforced beams.Both the ANSYS finite element analysis model and flexural capacity model of corroded beam with flexural and shear strengthening are established.Finally,the reinforcement area of steel plate is derived,and the formula of anchorage failure is given.(1)12 corroded and reinforced beams are designed to analysis the force condition of test beams in the situation of secondary corrosion,reinforcing mode and cover thickness,and are employed to explore the impact of the above three factors on crack,deflection,strain,failure characteristics and bearing capacity of the component.(2)Based on the spring element combin39 that can simulate the bond-Slip Behavior between the reinforcement and concrete,and using ANSYS finite element analysis software to simulate the test beams numerically,this paper expounds the deflection,load-displacement curve,the stress and the regularity of crack in this model,and compared with experimental result,more consistent results have been obtained.(3)On the basis of slip between reinforcement and concrete,the coordination coefficient is introduced.Starting from the plate boundaries reinforcement rate,flexural capacity model of test beam is established in three different conditions.The normal damage test beams without end corrosion,the calculated value is in good agreement with experimental data.However,the bearing capacity is low for the End corrosion test beams.(4)Considering the importance of anchor bolt and steel plate,the anchor bolt spacing and the thickness of the steel plate are optimized by use of the previous research results and finite element respectively.Based on the plane section assumption,the maximum and minimum reinforcement area of steel plates are derived,and the bearing capacity formula of the anchor bolt is given.