Abstract: In this paper, it aims to study the relationship between the CFRP tendons resistance changing rate and the strain in different strain stages. The relationship formula of the resistance changing rate and the strain has been derived, which is based on the sensing principle of CFRP. Then, the initial resistance and volt-ampere characteristic curves of the samples were obtained from the axial tensile test on three bunches of CFRP tendons, which includes its resistance-strain behavior, the initial resistance and volt-ampere characteristic curves. Through studying the changing rate of resistance of the samples which varies with the strain in three different strain stages, the CFRP tendons sensitivity of the initial stage was obtained by linear fitting. Results show that: when the strain is less than 0.8%, the resistance changing rate changes rapidly with the strain, and shows a good linear relationship; when the strain varies from 0.8% to 2.4%, the changing speed comes lower; and when the strain is higher than 2.4%, the changing rate of resistance increases sharply, which leads to the specimen destroyed.

Key words: CFRP, piezoresistivity, resistance, strain, sensitivity