Study On Ductility Of Reinforced Concrete Flexural Members Strengthened With Partially Bonded CFRP

FRP used to reinforc concrete structure began in the middle of 1980s,the Swiss Confederation laboratory first used the CFRP reinforced concrete beams,followed by rapid development,deepening of the scholars,has been widely used in reinforced concrete structure FRP.With the increase of data,more and more people are familiar with,found that the use of FRP reinforced concrete beams when it can be obtained to improve the bearing capacity of bending,but also reduces the ductility,which are the two main features of it.In the application of engineering structure,the decrease of ductility is the main performance of brittle failure,and it is a kind of dangerous.In this paper,the influence factors of bearing capacity and ductility of reinforced concrete beams strengthened with carbon fiber reinforced polymer(CFRP)sheets are studied by comparing the experimental results.This research has a very good promotion and application value in practical engineering application.In this paper,a total of 6 test beams by experiment,an unreinforced contrast beam,There are 5 beams in the middle position is not part of the paste is 0,20,40,60,80cm reinforcement beam,the bending test of the six beam control variable method,the ultimate bearing capacity of the beam and the maximum the deflection and strain of CFRP and the beam side surface strain measurement.Through the analysis of the data processing,it is found that the beam is bigger in the cross section,the bearing capacity is improved,and the ductility is improved.The observation can be found in the damage form of it,in the span of the beam with larger part of the void,crack the bottom of it more,and the development is relatively slow,it is because of such a principle,the ductility of the structure can be improved.Based on the test operation,the characteristics of flexural reinforced concrete structure reinforcement part paste were studied and analyzed,test beams deflection of large part reinforcement paste,bending crack of central dense and cross,not paste parts of larger cracks more intensive,the greater the deflection in;from the loading process to test beam damage,some reinforcement beams strengthened with the stiffness of the beam is significantly increased,strengthening beam pressure in the process of crack development is relatively slow,the crack width is relatively small;the routine of paste beam are deduced and analyzed some reinforcement of flexural capacity the calculation formula of the beam and has carried on the simple verification with Chen and Teng formula,found to agree well with the test results.Of course,in this experiment,the CFRP material utilization rate did not reach the ideal state,which is not a good play to its characteristics,we should try to change the stress state,improve its utilization rate,which is one of the follow-up work of our researchers.