The Limit State of Concrete Failure

With most structural materials, and especially with concrete, we think about how's it going to fail? Right? You want to be able to observe concrete fail about to fail before it fails. So by observation, can you see what is the material start doing prior to it failing? Let's say in bending or in sheer. Is there an observable piece to that? Absolutely. And I'm really glad you bring this up on identifying modes of failure. That's a really great piece that good structural engineers are going to focus on. Not will it fail? How?