After looking at the collapsed condo report combined with its location on the beach IMO the root cause will be the result of corrosion of reinforcement due to salt water. Both carried in on vehicles into the parking garage combined with wind blown sea salt and possible salt water flooding during past hurricanes. Parking garages where road salt is used in winter is a death sentence to reinforced concrete slabs and columns. Southern coastal regions may not have road salt, but have constant sea salt issues. Heavily reinforced concrete columns have significant vertical steel, but smaller horizontal hoops or spiral steel is needed to keep the vertical steel from bowing out. The vertical steel can be #11 up to #18 bars, but the outer cage is typically very small diameter steel. If this outer cage rusted the vertical steel will bow out like a whiskey barrel bows out in the middle.
Good analysis Randy. Sea salt air is one of the most destructive forces to materials. It’s the main reason Post-Tensioned construction is encapsulated in those areas.
I agree, very good assessment from afar.
Here is an interesting article, just a few photos from the pool guys reveals massive issues in my opinion.