Ultimate strength assessment of cracked stiffened box girders subjected to extreme cyclic bending moments

This paper aims at obtaining insight on the ultimate strength characteristic of stiffened box girder under extreme cyclic bending. Nonlinear finite element analysis is performed to investigate the ultimate bending moment of cracked stiffened box girder. It is presumed that the preset crack is a through-thickness and transverse crack on the deck, the corresponding five types of cracked models are analyzed. The effects of crack type, crack length and crack location under cyclic loads are examined. Two load patterns are considered in this study, and crack propagation under bi-directional cyclic bending is simulated by applying the element erosion approach. The individual and coupling effects of fatigue crack damage and accumulated plastic damage on the ultimate bending moment of stiffened box girders are discussed. The mechanism of ultimate strength reduction under extreme cyclic bending is analyzed, it could be concluded that ultimate strength reduction is attributed to the coupling effect of these two damages and its applicability is verified by other stiffened box girders.