Time-Progressive Dynamic Assessment of Abrupt Cable-Breakage Events on Cable-Stayed Bridges

Although long-span bridges are usually designed with sufficient structural redundancy, particular concerns arise about the abrupt breakage of bridge cables, which may cause progressive failure such as zipper-like collapse. The time-progressive nonlinear dynamic analysis approach is proposed to investigate the abrupt cable-breakage event of a cable-stayed bridge. Compared with existing studies, the proposed methodology focuses on the simulation of cable loss scenarios in a more realistic manner through incorporating stochastic moving traffic loads, dynamic bridge-vehicle interactions, and associated dynamic initial states of the abrupt cable-breakage event. Several important issues associated with the proposed simulation methodology, such as the finite-element modeling option of cable breakage, different initial states of cable breakage, nonlinearity, and traffic loads, are investigated through a prototype bridge example. Finally, the response envelopes in terms of moments and stresses along the whole bridge are obtained and compared by means of the proposed nonlinear dynamic simulation approach, the static approach, and the pseudodynamic approach with a dynamic amplification factor of 2.0 as recommended by the Post-Tensioning Institute. (C) 2014 American Society of Civil Engineers.