That's exactly what we are talking about with bridge design: Overbuilding it so you can lose an element without the bridge collapsing.

There really isn't a concept of a bridge "failing gracefully". Any failure is a disaster. You can talk about a bridge being functional even after it becomes weakened by the elements or overloading or poor maintenance or some other condition, but that is another case of overbuilding.

I guess what I'm saying is that software and bridges are not very similar.