Trans-Scale Computational Model for Fatigue Behavior Simulation of Orthotropic Steel Decks

Abstract

A new three-dimensional trans-scale crack growth model, developed from the microscale to macroscale, is presented based on the concept of restraining stress zone. It aims to simulate the growth behaviors of fatigue cracks in a welded joint of orthotropic steel decks. In the study, the crack shape was first simplified as a semielliptical surface crack, and analyzed in a finite-element mode considering the trans-scale stress intensity factors (SIFs). Subsequently, the trans-scale SIFs served as controlling parameters for the propagation of fatigue crack from the microscale to macroscale. The proposed model can simulate the overall process of fatigue failure of orthotropic steel deck details. Comparison between numerical simulations and results from the experimental S-N curves given in the literature provides two conclusions: (1) the three-dimensional trans-scale crack growth model accurately depicts the trans-scale behaviors of fatigue failure of the weld joint between the longitudinal ribs and deck plate of the orthotropic steel deck; and (2) the model well explained the scatter phenomenon of the fatigue test data due to the microscopic effects. In addition, the initial microdefects have a significant influence on the fatigue life, and the microscopic effects in a fatigue process can be considered by the proposed model.