A Study on the Fatigue Failure Characteristics of Steel Bridge Deck Pavement Layers under Dynamic Loads

In response to the common interlaminar shear and delamination defects in the pavement of long-span steel bridges, this paper investigates the interface fatigue failure mechanism of the “SMA-13 + epoxy resin + orthotropic steel plate” system. Static direct shear tests indicate that the optimal application rate of epoxy resin is 1.5 kg/m2, and that elevated temperatures cause the failure mode to transition from brittle fracture to ductile creep. Based on full-factorial dynamic shear fatigue tests, this study discarded subjective empirical thresholds and innovatively proposed the “geometric tangent method” to quantitatively define fatigue life. Analysis of variance (ANOVA) revealed that the sensitivity of each factor to fatigue life, in descending order, is: temperature > loading frequency > stress level. Consequently, this study developed a high-precision, multifactorial life prediction model (R2 = 0.962), providing a scientific basis for evaluating the long-term service performance of bridge decks. Further validation using experimental data is required.