What does Structural engineering comprise of?

What does Structural engineering comprise of?

Designing things to be strong enough; for their dead load, strong enough for a snow load or an earthquake or a hurricane winds and making the foundation big enough that it will not sink into the earth, knowing how much steel/concrete/wood to use and where to use it for the most strength. You even look at floor vibration. Between 4 and 8 vibrations per second makes people feel uneasy, like the floor might give way.