SFCharlie, Unfortunately while they are convenient, searchable codes are a two-edged sword. I find many engineers avoid reading the full code and hence miss understanding the interactions of the various sections when it is so convenient to simply search up some detail they need at any given moment, copy/paste and move on.
Redundancy in my experience is not practical in run of the line commercial structures or even offshore platforms. It is not something that is designed into a structure, but something that results indirectly from the normal design process, such as designing a building to separately resist both N-S and E-W wind, but knowing that winds never blow from the both the north AND east at the same time. Or the low probability of having all floors with full live load applied. I've personally never designed any structure to be capable of standing if, for example a floor beam let go and fell onto the lower one, or for some armored car leaving the street at 60mph, crashing into and taking out a first floor column. If an offshore platform loses one of 4 or even 6 legs, its probably going to go totally under, but might survive because the current only flows one direction at a time. While waves could theoretically strike from multiple directions, that was never a design condition. I have designed various control buildings in refineries for blast shock requirements, but that has been the limit of my designed-in redundancy, which isn't really considered to be redundancy if it is a realistic design scenario.
