Research Of Reinforced Concrete T-beams Strengthened With BFRP

Basalt Fiber-Reinforced Polymer (BFRP) is a new kind of structural materials. Itpopular because it present several advantages，such as high tensile strength, low density,high temperature resistance, low moisture absorptivity, good dielectric property andcorrosion resistance．At present，the study and application of BFRP in the field of civilengineering are still at the initial stages，and the performances of BFRP strengtheningreinforced concrete beams are still unclear．But，in the future it will be a large number ofuse in civil engineering applications because of its numerous advantages. So, this paperis engaged to investigate the flexural behavior of reinforced concrete T-beams streng-thened with externally bonded BFRP sheets．Based on the experiment of six RC T-beams，this paper from the test beams’ failuretype, ultimate flexural capacity, bending stiffness，Mid-span deflection, ductility, cracksdevelopment and so on to initially researched the effects of RC T-beams strengthenedwith externally bonded BFRP sheets; and analyzed the effect of parameters on the flex-ural behavior and failure type of the test beams，which are considered in test beams suchas different height of flange，way of anchoring，different conditions of BFRP amountand so on; and derived the calculating formula for the ultimate flexural capacity, and thefeasibility of these formula have been verified well by the test results．The following are the main conclusion in this paper：1) Three failure modes are appeared in RC T-beams strengthened with externallybonded BFRP sheets, including the BFRP is pulled off and concrete is crushed; theBFRP is not pulled off and concrete is crushed; the bond failure is appeared betweenreinforced concrete T-beams and BFRP before the BFRP is pulled off. The flat sectionassume is still established in these failure modes by analyzing the test data.2) In the case of the same other conditions, the RC T-beams strengthened with ex-ternally bonded BFRP sheets’ cracking load, yield load, ultimate load and bendingstiffness will increase with the more the amount of fabric, more reliable way of anchor-ing and more higher of flange height; and reduced accordingly of the Mid-span deflec-tion, ductility, crack spacing and maximum crack width.3) Based on the existent theoretics of design code for strengthening concrete struc-ture and the technical specification for strengthening concrete structure for CFRP lami-nate, introduced the concept of stripping ultimate strain and reinforcing rate, this paper has developed the calculating formula for the cracking load, yield load and ultimateflexural capacity to the different failure mode，and through the compare between testresults and calculating results，the calculating formula’s applicability has been proved.and the calculated value is conservative.