Experimental Study On Bending Resistance Of Corroded Steel Beams Strengthened With CFRP Plate

Steel structures are widely used in various civil engineering fields because of their advantages of high material strength,good plastic toughness,uniform material quality,simple manufacturing,short construction period,and light structural quality.However,steel structures that have been exposed to corrosive environments for a long time avoid corrosion resulting in the degradation of its bearing capacity through protective and structural measures.How to effectively reinforce corroded steel structures and improve its bearing performance is a key issue to be solved in the field of civil engineering.In this paper,steel beams were accelerated corrosion by the neutral salt spray test,the use of experimental research,numerical simulation,theoretical analysis combined methods to study the mechanism that the tension zone of corroded steel beams reinforced with the CFRP enhance its bending performance.The main contents are as follows:Six simply-supported steel beams were tested on the bending strength of positive cross section(one was uncorroded steel beams,one was corroded steel beams,and four were corroded steel beams reinforced with CFRP plates).The effect of parameters such as corrosion agree in the tension zon and the prestress of CFRP plates on the bending properties was studied.Results show that CFRP plates can effectively improve the the bending strength of corroded steel beams.The failure of corroded steel beams reinforced with CFRP plates was due to the tearing of CFRP plates.The fracture position of CFRP plates mostly occurs at the loading point.After the steel beam is damaged,the CFRP plate will have a longitudinal slip of 5~10mm.Compared with the non-prestressed CFRP plate,the bearing capacity of steel beams strengthened with the prestressed CFRP plates had have been greatly improved.The ultimate bearing capacity of steel beams strengthened with 15% prestressed CFRP plates increased by 21%.According to the characteristics of corroded steel beams reinforced by CFRP plates,a finite element analysis model of steel beams reinforced with CFRP plates was established.Based on the verification of the finite element analysis model using the test results,the finite element analysis model was used to analyze the influence of thickness,width,length and elastic modulus on the bending strength of steel beams.The optimal parameters of the tension zone of steel beams strengthened with CFRP plates are explored,which provides a theoretical basis for the design of CFRP plates for reinforceing corroded steel beams,and further improvs the design theory of strengthening of existing steel structures.On the basis of experimental research and finite element analysis,a calculation model for the bearing capacity of corroded steel beams reinforced with CFRP plates was established.The calculated results of the model are in good agreement with the experimental results.