The SUperdome was designed from the ground-up to be a hurricane shelter.
People should be aware that while a large substantial structure with upper floors elevated and designed for high winds is a good choice for mass sheltering of people, the actual impact of a storm such as this is not an event that ANY building is designed to withstand with certainty.
No engineering for wind pressure can take into account the wind carried large debris, the battering of wind gusts and the impact of weak-points created by those items.
Only one parapet cap, edge of a roof, damaged vent or area impacted by a flying refrigerator is needed for any structure to have a point of local failure and thus a weak point where the winds attack the entire structure.
Knowing codes, building construction and the like, I have a pretty clear understanding of the limitations of that phrase, "designed-for". If this developes as the last six hours have led us to believe, this will probably be a disaster of a size that most don't contemplate currently.