The Experimental Study On Stiffness And Interfacial Properties Of Steel Beams Strengthened With CFRP Plates

Strengthening the steel structures with Carbon Fiber Reinforced Polymers (CFRP) is one kind of reinforcement technologies which has unique advantages. It has become a hot research issue at home and abroad recently. At present, there are many researches on the calculation methods of stiffness and adhesive interface stress for composite steel beam after strengthening without considering the effect of initial stress and the bond slip between CFRP plates and the steel beams. Also the forms of the interface stress calculation formulas are too complex to use. This paper corrected the existing calculation formulas by experimental study and finite element software analysis, which provide theoretical basis for engineering application.After comparing and summarizing the massive research achievements at home and abroad, this paper took the composite steel beam stiffness calculation formula in "FRP composites Life extension and strengthening of metallic structures"proposed by British Institution of Civil Engineers (ICE),and took the interface stress calculation formula in"Strengthening metallic structures using externally bonded fibre-reinforced polymers"pToposed by Construction Industry Research and Information Association (CIRIA) as researching theoretical basis.Then it conducted single lap-shear test and flexural static loading test of the steel beams strengthened with CFRP plates considering initial stress. According to the test results, this paper corrected the stiffness calculation formula proposed by ICE after considering the effect of bond slip between CFRP plates and the steel beams. It also validated the interface stress calculation formula proposed by CIRIA. Finally, this paper carried out the numerical simulation analysis of flexural static loading test using the ANSYS finite element analysis software.This subject is supported by national standard "Design code for strengthening steel structure" and the research results of this paper will provide theoretical and experimental basis for compiling this standard.