Experimental Study On Strengthened RC Frame Beam-column Joints

After several decades of rapid development,the domestic construction Industry has already entered into its mid and late stage.Some buildings have been seriously damaged due to the unregulated construction and unreasonable use.Beam-column joint is the most important part of frame structure.It is easy to happen to brittle failure on earthquake action. Therefore,the study of reinforced beam-column joints is the emphasis in reinforcement study. However,beam-column joint belongs to a complex structure.The complex structure shape and force relation restrict the development of study on beam-column joints reinforcement.And there is a huge dispute on the reinforcing effect of beam-column joint.A new joint reinforcement method is carried out in the experiment.After installing external cable on the beam-column joint,the system of the structure has been changed.In this way,it avoids to work on the beam-column joint area directly and reinforce the beam-column joint as well.By using the method of theoretical research and test study,the dissipative and shear performance of the reinforced beam-column joint is studied.Moreover,three specimens with the same sizes,the same reinforcement ratio and hoop reinforcement ration are made,and two of which are reinforced in different mode.It exerts constant axial force on beam end and low cyclic loading on cantilevered Beam.Beam load and displacement,mode of failure, cracking behavior and the steel strain change are investigated in this article.Through analyzing and evaluating the test results,this article comparatively studies the cracking load,yield load,ultimate bearing capacity,beam load,hysteresis property and the features of envelope line,ductility and energy dissipation of each test piece.The experiment results show that the frame aseismatic and shear behavior of core area have been improved noticeably.Reinforced frame cracks later than before and more distributed.It proves that through reinforcement,the external force exerted on the beam-column joint has been reduced and the beam-column joint's function has been improved.Based on the experiment and existing research results,this article theoretically analyzes the anti-shear capacity of reinforced beam-column joints and deducts the formula.The experimental results agree with simulative results well.Furthermore,it analyzes the factors that affect the reinforced area of beam-column joint and make the reinforcement design and research more pertinent.