Experimental Study Of Shear Strengthening Techniques Of RC Beams By High-strength Prestressed Steel Wire Ropes

At present,some bridges cannot meet the demand of strength because of the lack of theoretical knowledge in the past,defect of construction quality and overload,and need to be repaired,reinforced or rebuilt.Since the rebuilding of bridge structure needs a great cost,the research on strengthening and retrofitting structures are being more and more important in the world.Shear failure is very common in the failures modes of bridge structures,which is fragile leading to rapid destruction and extremely insecurity.The shear strengthening method of using prestressed steel wire ropes is a kind of new technology.It has been widely applied into practical engineering because of the good ductility,light quality and convenience.However,because of different factors about today's technology or craft,reinforcing with prestressed steel wire ropes alone cannot meet the requirement of strengthening concrete beams.In order to solve the problem of the insufficiency of reinforcing with prestressed steel wire ropes,on the basis of the single method,this dissertation does research as follows:The shear strengthening method of combing prestressed steel wire ropes and high-strength screws is proposed,combing which with steel plate at the bottom of the structure,the flexural and shear strengthening method is proposed at the same time.And both of the construction crafts are explored.The mechanical performance of 7 reinforced concrete beams strengthened by single shear strengthening method,combined shear strengthening method and combined lexural and shear strengthening method is researched via experiments,that confirms the strengthening methods proposed are feasible and effective.As a result,the failure mode of strengthened beams changes into plastic failure from fragile failure.And this combination of prestressed steel wire ropes and screws increases the cracking load,the yield load,the ultimate load and ductility of the beams.And the combination of prestressed steel wire ropes,screws and steel plate increases the debonding damage load and global ultimate load.A nonlinear finite element model is proposed to simulate the basic mechanical performance of the strengthened beams,which is verified to be effective by comparing with the experimental results.