Experimental Study On Behavior Of RC Beams Strengthened With High-strength Steel Stranded Wire Mesh And ECC

Engineered cementitious composites(ECC)is one of the advanced materials which was modified by microscopic mechanics and shows the character of the multiple cracking and tensile strain-hardening behavior under tensile and shear load.In this paper,ECC and high strength steel stranded wire mesh are combined to form a new strengthening technique to improve the safety,durability and sustainability of reinforced members.The experimental study was conducted to investigate the flexural behavior and the theory of RC beams strengthened with high-strength steel stranded wire mesh and ECC.Four beams strengthened with high-strength steel stranded wire mesh and ECC,four beams strengthened with high-strength steel stranded wire mesh and polymer mortar and one comparative RC beams that were designed and produced.The main parameters included the number of steel stand,with or without initial damage and the type of materials that combining with highstrength steel stranded wire mesh.The results showed that:(1)The high-strength steel stranded wire mesh and ECC can effectively improve the flexural load-carrying capacity of the beams with or without initial damage and that increases with the increase of the number of high-strength steel strand.The maximum increase in flexural capacity of the specimens which without initial damage was 60.9%,and that of the specimen with initial damage was 66.5%.(2)Compared with high-strength steel stranded wire mesh and polymer mortar strengthening technique,high-strength steel stranded wire mesh and ECC strengthening technique has a more obvious limiting effect on cracks.Under the same load level,the beams strengthened with high-strength steel stranded wire mesh and ECC has a smaller crack width and spacing.It's also more effective to limit the crack development of concrete layer that can better improve the durability of the RC beam.(3)The flexural strengthening technique does not increase the initial stiffness of RC beam significantly,but will increase the stiffness of section at the later loading stage,delay the growth of reinforcement strain and limit the development of cracks.(4)Using high-strength steel stranded wire mesh and ECC will decrease the ductility of the flexural strengthened specimens than the comparative RC beam.(5)Based on the test results,the failure mode and specification,the design formula of flexural load-carrying capacity was proposed,and the calculated results agree well with the test results.The experimental study was conducted to investigate the shear behavior of RC beams strengthened with high-strength steel stranded wire mesh and ECC.Four beams strengthened with high-strength steel stranded wire mesh and ECC,four beams strengthened with highstrength steel stranded wire mesh and polymer mortar and one comparative RC beams that were designed and produced.The main parameters included reinforcement ratio,with or without initial damage and the type of materials that combining with high-strength steel stranded wire mesh.The results showed that:(1)The high-strength steel stranded wire mesh and ECC can effectively improve the shear load-carrying capacity of the beams with or without initial damage and that increases with the increase of the reinforcement ratio.The maximum increase in shear capacity of the specimens which without initial damage was 45.2%,and that of the specimen with initial damage was 32.7%.(2)The shear strengthening technique has little influence on the initial stiffness of the shear strengthened specimens,but it will play an important role in the late stiffness.(3)Compared with high-strength steel stranded wire mesh and polymer mortar strengthening technique,high-strength steel stranded wire mesh and ECC strengthening technique has a more obvious limiting effect on cracks.Under the same load level,the beams strengthened with high-strength steel stranded wire mesh and ECC has a smaller crack width and spacing,which can better improve the durability of the RC beam.(4)Using high-strength steel stranded wire mesh and ECC will increase the ductility of the shear strengthened specimens than the comparative RC beam.(5)Based on the test results and the specification,the design formula of shear loadcarrying capacity was proposed,and the calculated results agree well with the test results.