Flexural strength of steel I-beams reinforced with CFRP sheets at tension flange

Abstract

The use of modern Carbon Fiber Reinforced Polymer (CFRP) to strengthen and repair steel beams in flexure has been rapidly increased within the past few years. This technique benefits from light-weight and extra-strong CFRP material to enhance the flexural capacity of cross section. To study the reinforcing effect of CFRP, one hundred and seventy-eight models were analyzed to cover six variables representing the common problem parameters; the variables were the slenderness ratio of web (hw/tw), the mono-symmetric ratio of I-beam (ψ), the area of CFRP (Acfrp), the modulus of elasticity of CFRP (Ecfrp), the tensile strength of CFRP (Fucfrp), and the length of CFRP sheet (Lcfrp). The adhesive properties used in parametric analysis were determined from experimental tests conducted for double-strap steel-to-CFRP joints with various bond lengths (50 to 200 mm), and the proposed model constructed using the general finite element program, ANSYS 17, was verified with experimental tests of full-scale steel beams reinforced with CFRP. The parametric study revealed that CFRP sheets were very efficient in reinforcing compact mono-symmetric sections, whereas the enhancement in beams with non-compact sections was very small. CFRP sheets were able to reach its ultimate strength provided that enough bond length was ensured. Analytical procedure to calculate the flexural strength of steel I-shaped beams reinforced with CFRP sheets at tension flange was presented.