Abstract: In order to obtain the fatigue stress value reflecting the real response state of reinforced concrete beams, an effective fatigue stress parameter value model based on real-time strain monitoring information was proposed. In view of the cyclic characteristics of real-time strain monitoring data, it was simplified into standard cyclic blocks. Low-frequency and high-frequency operations were carried out to realize the extraction of real structural data. Based on “Fourier transform”, the transformation analysis and authenticity verification were carried out, and the realstrain data was obtained. Based on the characteristic of dynamic strain standard cyclic block, the main peak value was only considered in the statistic of random wave stress peak value, the material ratio limit was used as the starting point of reading instead of the mean line. The true fatigue stress characteristic value ofbeams could be obtained by transformation. Without affecting the fatigue damage of beams, based on the principle of strain energy and damage equivalence, the variable-amplitude stress spectrum was converted into the equivalent fatigue stress spectrum. Finally, the “real-time state analysis model” for evaluating the current damage status of beams and the “predictive trend analysis model” for predicting the later damage status of beams were established.

Key words: real-time fatigue strain, effective fatigue stress, long-term monitoring, fatigue property, reinforced concrete beam