High strength concrete is widely used in very important civil and industrial buildings

so it is ur- gently needed to investigate and solve the problem how to maintain and strengthen these buildings.An ef- fective and popular method for strengthening existing concrete buildings is to bond GFRP on the surface of concrete.However

the interracial failure mechanism has been rarely studied especially in the case of high strength concrete.In this paper

41 single-face shear type specimens with different concrete strength

bond lengths

bond width and GFRP stiffness are tested.By analyzing the tested result

a model of bond strength which fits the result well is developed with a new width ratio coefficient and compared with Chen- Teng’s formulas.Several bond strength models available are tested to predict the bond strength between GFRP and high strength concrete.The strain profile of interface is presented and the analytical strain dis- tributions agree well with the experimental ones.