The reports at the time (of the Taiwan bridge collapse) put the blame on poor maintenance and inspection. There was some criticism of the design in this case but it was not the deciding factor, but as this is from my memory it is probably best if people read the reports themselves and reach their own conclusions.
Behind these shocking events people wonder: "why so many bridges fail? " Is this a Structural Engineers' fault? A bad design or structural negligency put people's life at risk!