Study On Reinforcement Behavior Of Reinforced Concrete Beam-column Joints Strengthened With Carbon Fiber Reinforced Composites

The reinforcement history of the building structure has been going on for several decades.After many people have studied and practiced,it has formed a method of changing the force transmission method,adding the fulcrum reinforcement method,increasing the cross section method,outsourcing steel method,prestressing method,unloading reinforcement method,external paste fiber reinforcement method.Carbon fiber reinforced composite(CFRP)reinforced concrete(RC)structure began in the the eighties of the twentieth century,the first using CFRP reinforcement structure of the country is Japan in the construction field.The CFRP has a light weight,high strength,flexible modulus and other advantages,so it received the attention of academia and the construction industry,and was gradually promoted.Nowadays,many researchers in the field of architecture study the RC structures and components of the CFRP,the main research areas include beams,columns and plates,the focus of the study is shear performance and bending resistance.In recent years,earthquakes are frequent,the beam-column joints of the frame are weak structures,it is easy to damage under the earthquake.In view of this situation,this paper studies the seismic performance of CFRP reinforced concrete composite structures.The main research object of this paper is beam column joints,the two beams and columns are taken from the edge and the middle part of the frame structure respectively.The simulated loading method is a low-cycle repeated load,which can well reflect the form of seismic load.The main research purpose of the paper is the comparison of beam column joints before and after reinforcement of shear strength,bearing capacity,ductility,strength,stiffness,energy dissipation capacity,etc.The tool to be used for modeling is ABAQUS,the results to be used should include hysteresis curve,CFRP stress cloud,concrete third principal stress cloud,reinforcement stress process,etc.Finally,the resulting data are validated and analyzed to arrive at the final conclusion.In order to reduce the effect of stirrups on the simulation results,combined with the experience of previous research,in the modeling process using the best stirrup rate,in order to make CFRP more consistent with the assumptions,select the excellent performance of CFRP.The specific work of the article is as follows:(1)First,this paper briefly introduces the failure form of the node,summarizes the traditional structural reinforcement method,and summarizes the research status of CFRP reinforced concrete structure,and summarizes the domestic and international research status of reinforced concrete beams and columns with carbon fiber reinforced composite materials.(2)Secondly,the theory of finite element analysis of reinforced concrete is introduced,and the unit model and fracture model of concrete are introduced respectively.The paper introduces the types of beam-column joints and introduces its mechanism of force,summarizes several main factors that affect the seismic performance of beam-column joints,and sums up the formula of shear capacity of reinforced concrete frame structures under earthquake.(3)Thirdly,according to the seismic design code,the ABAQUS software was used to simulate the beam-column joint model before and after reinforcement.The failure modes,CFRP stress distribution,concrete stress distribution,ultimate load,ultimate displacement,hysteresis curve and ductility coefficient are analyzed.(4)Finally,the influence of the CFRP paste on the bearing capacity of the specimen is obtained by analyzing the simulation results of the cross-joint of the frame structure.Finally,the effect of CFRP layer on the bearing capacity is summarized.Comparing the results of simulation,the best way to paste and the most economical use of CFRP is obtained.