Effect of the Traffic Load Distribution on the Progressive Collapse of a Cable-Stayed Bridge Under Blast Load

The advanced coupled finite element models can be used to model the structures and the extreme load of air blast as well as the interaction between them. However, the structural response of long-span bridges can be significantly influenced by the magnitude and location of blast load and pattern and magnitude of traffic load along and across the deck. In addition, the previous studies considered the cable loss when the bridge is intact, however the damage of explosion on a bridge causes new deformation and characteristics. Accordingly, in this study, the effect of five different traffic loading cases has been investigated on the maximum response of a cable-stayed bridge under eight different blast scenarios and the possibility of progressive collapse has been evaluated. It is concluded that the traffic load configurations on the bridge can vary maximum actions on different components up to 30%. Cable loss or anchorage zone destruction under blast loading scenarios are observed independent of the traffic load distribution. Meanwhile, the progressive collapse of bridge due to cable loss likely occurs in a number of the blast scenarios. Moreover, the vulnerability of more than one cable loss is clearly observed in some cases and designing bridges based on only one cable loss is not safe if the occurrence of hazards on the bridge is unavoidable. Besides, two symmetric traffic loading scenarios (i.e. 50% of traffic load applied on the entire bridge, and 50% of the traffic load only applied on middle span) are identified as the most critical in terms of the bridge components response.