Abstract:
Due to the lateral high-cycle fatigue induced by long-term repeated crane operations, the concrete-filled steel tubular (CFST) members in heavy industrial buildings are prone to interfacial debonding between steel tube and concrete. Nevertheless, the post-fatigue bonding behavior of CFST interfaces under transverse cyclic loading remains inadequately investigated. This study presents an experimental program involving lateral high-cycle fatigue and subsequent push-out tests on nine CFST specimens, examining the effects of fatigue cycles, fatigue peak load, and aspect ratio on interfacial performance. The results demonstrate that the stiffness degradation progresses with the increasing of fatigue cycles, fatigue peak load, and aspect ratio, conforming to the empirical model K_\rm f=1-0.013\mathrm\lg N . Push-out tests reveal that the influence of fatigue cycles on bonding behavior exhibits stage characteristics: a pronounced decline in ultimate bond strength occurs before reaching 50,000 cycles; beyond this threshold, partial specimen strength recovery occurs, though the values are lower than those of non-fatigued specimens, while the ultimate displacement exhibits continuous augmentation. The relationship between fatigue peak load and bond strength is nonlinear, characterized by a minimum value at 0.1 times the flexural capacity, followed by a progressive increase within the 0.1–0.4 range. When the aspect ratio increases from 6 to 8, the ultimate bond strength decreases by 9.22%, and the ultimate displacement decreases by 0.3 mm. The research results reveal the degradation mechanism of the bonding performance at the steel-concrete interface under lateral high-cycle fatigue, providing experimental evidence for the fatigue design and safety assessment of steel-concrete components in industrial buildings.