Effect of Dynamic Unloading of Cables in Collapse Progression Through a Cable Stayed Bridge

Progressive collapse is a continuous spread and magnification of localized failure in structures, caused by an accidental load, resulting in a cascade of failure affecting a large portion of the structure. Although alternate path method is the most widely used method to increase the structural robustness of bare frame structures against progressive collapse, it should be further developed for other structures, and especially cable stayed bridges as they are highly sensitive to dynamic impact loading. This paper demonstrates modelling and analysis of a typical cable stayed bridge through two important analytical procedures, i.e., nonlinear static and nonlinear dynamic. Furthermore, the response of the structural model is discussed for multiple types of cable loss cases. Two different progressive collapse patterns are identified for nonlinear static and dynamic procedures as the dynamic unloading function is considered in the dynamic analysis procedure. The results also indicate a decrease in the possibility of failure progression of the cable stayed model when the location of the failed cables is closer to the pylon.