Study On The Flexural Performance Of T-shaped Concrete Beams Strengthened With Different Strengthening Methods

With the continuous development of transportation industry in our country,a large number of low grade bridges were rebuilt.Many Bridges structure performance have taken great changes in recent years.Some bridges have appeared different degree of damage,and even its bearing capacity has greatly reduced and evolved into dangerous bridge.This situation caused great bottleneck for the development of transportation industry in China and a lot of bridges would reach using life in the next 10 to 20 years if we did not controll.This paper studied on flexural performance of T-shaped concrete beams strengthened with different methods.Studying on the change rule of T-shaped concrete beams experiment phenomena,characteristic load,bending,strain and mid-span deflection before and after strengthening.Analysing the change rule of flexural performance of T-shaped concrete beams strengthened with different amount of reinforcement,concrete grade,reinforcement ratio and U-shaped hoop.In order to study on flexural performance and influence factors of T-shaped concrete beams strengthened with the Carbon Fiber Reinforced Polymer(CFRP),this paper designed eight T-shaped concrete beams and considered the amount of CFRP fabric reinforcement,reinforcement ratio,concrete grade,U-shaped hoop and examined the several factors that effact on strengthened beam failure pattern,flexural rigidity,strain and mid-span deflection.Results showed that strengthened T-shaped concrete beams failure pattern was well and all showed the failure pattern of rebar yield,CFRP fabric tensile,compressive zone of concrete crushed.The tensile of concrete crack section beared by CFRP fabric and rebar.The destruction process of strengthened specimen can be divided into three stages,elastic stage,working with cracks stage,damage stage.The improvement of characteristic load amplitude was the largest when increasing CFRP fabric reinforcement.The CFRP fabric anchoring was well when increasing U-shaped hoop.So U-shaped hoop anchoring was working.Strengthened specimens bending rigidity have small difference compare with standard specimens before rebar yield.Strengthened specimens flexural rigidity was obviously improved after rebar yield.Strengthened specimens have small difference compared with standard specimens in rebar strain before the concrete crack and every group strengthened specimens have small difference in CFRP fabric strain.The amount of CFRP fabric reinforcement and reinforcement ratio have a great influence on rebar strain and CFRP fabric strain.Concrete grade and U-shaped hoop have a little effect on strengthened specimens rebar strain and CFRP fabric strain.Strengthened CFRP fabric was mainly limiting deflection from yield to ultimate stage,but it has a little effect on deflection before crack and from crack to yield.In order to study on flexural performance and influence factors of T-shaped concrete beams strengthened with the steel plate,this paper designed eight T-shaped concrete beams and considered the amount of steel plate reinforcement,reinforcement ratio,concrete grade,U-shaped hoop and examined the several factors that effact on strengthened beam failure pattern,flexural rigidity,strain and mid-span deflection.Results showed that strengthened T-shaped concrete beams failure pattern was well and all showed the failure pattern of concrete crack,steel plate tensile,compressive zone of concrete crushed.The tensile of concrete crack section beared by steel plate and rebar.The destruction process of strengthened specimen can be divided into three stages,elastic stage,working with cracks stage,damage stage.The improvement of characteristic load amplitude was the largest when increasing steel plate reinforcement.The steel plate anchoring was well when increasing U-shaped hoop.So U-shaped hoop anchoring was working.Strengthened specimens bending rigidity have small difference compare with standard specimens before concrete crack.Strengthened specimens flexural rigidity was obviously improved after concrete crack.Strengthened specimens have small difference compared with standard specimens in rebar strain before the concrete crack and every group strengthened specimens have small difference in steel plate strain.The amount of steel plate reinforcement and reinforcement ratio have a great influence on rebar strain and steel plate strain.Concrete grade and U-shaped hoop have a little effect on strengthened specimens rebar strain and steel plate strain.Specimens strengthened with angle steel have a good ability of deformation.Strengthened specimens have small difference compare with standard specimens in yield deflection and ultimate deflection.In order to study on flexural performance and influence factors of T-shaped concrete beams strengthened with the angle steel,this paper designed eight T-shaped concrete beams and considered the amount of angle steel reinforcement,reinforcement ratio,concrete grade,U-shaped hoop and examined the several factors that effact on strengthened beam failure pattern,flexural rigidity,strain and mid-span deflection.Results showed that strengthened T-shaped concrete beams failure pattern was well and all showed the failure pattern of concrete crack,angle steel tensile,compressive zone of concrete crushed.The tensile of concrete crack section beared by angle steel and rebar.The destruction process of strengthened specimen can be divided into three stages,elastic stage,working with cracks stage,damage stage.The improvement of characteristic load amplitude was the largest when increasing angle steel reinforcement.The angle steel anchoring was well when increasing U-shaped hoop.So U-shaped hoop anchoring was working.Strengthened specimens bending rigidity have small difference compare with standard specimens before concrete crack.Strengthened specimens flexural rigidity was obviously improved after concrete crack.Strengthened specimens have small difference compared with standard specimens in rebar strain before the concrete crack and every group strengthened specimens have small difference in angle steel strain.The amount of angle steel reinforcement and reinforcement ratio have a great influence on rebar strain and angle steel strain.Concrete grade and U-shaped hoop have a little effect on strengthened specimens rebar strain and angle steel strain.Specimens strengthened with angle steel have a good ability of deformation.Strengthened specimens have small difference compare with standard specimens in yield deflection and ultimate deflection.