[unavoidable]

Like aircraft disasters, most civil/structural engineering disasters have more than one "cause". There is not always a satisfying answer or a single "smoking gun". A bunch of things usually have to go wrong at the same time for a building to collapse catastrophically. Building codes and engineering designs have a lot of assumptions built in, including an assumption that construction does not follow the drawings exactly. But other assumptions include lack of corrosion to a degree, regular maintenance, proper materials specifications, no subsequent modifications, a particular load pattern, etc.

Even then, most buildings are not really designed for much more than 60 or 70 years. Of course, most buildings are also supposed to be designed in such a way that even if it fails, it does not result in a cascading failure. The fact that this particular kind of disaster (apparently spontaneous collapse) is so rare is what makes it newsworthy.

[secabeen]

Yeah, I've read _Normal Accidents_, and I follow AdmiralCloudberg's aircraft disasters. There isn't always a satisfying answer, but there often is, or at least one factor that's most damning.