Extremely low cycle fatigue prediction of steel beam-to-column connection by using a micro-mechanics based fracture model

Beam-to-column connections in steel moment resisting frames may suffer extremely low cycle fatigue (ELCF) during earthquakes. The cyclic void growth model (CVGM), a micro-mechanics based fracture model, was adopted to predict ELCF fracture of the beam-to-column connections. The validity of the model was verified by the experimental results of nine full-scale connection tests. In addition, refined finite element model was employed to simulate the cyclic behaviors of the connection tests, and the CVGM fracture index was calculated based on the stress and strain time histories. The number of cycles and the cumulative deformations to ELCF fracture predicted by CVGM agreed well with the experimental results. The presented methodology showed reasonable good accuracy to predict ELCF fracture of beam-to-column connection under inelastic cyclic loadings.

► Earthquake induced fracture is categorized into extremely low cycle fatigue (ELCF).
► Nine full-scale steel connections are tested under inelastic cyclic loading.
► Micromechanics based fracture model CVGM is integrated into the FEA model.
► Increase of fracture demand and degradation of material capacity are considered.
► The method shows good accuracy in ELCF fracture prediction of the connections.