Also, all that civil engineers do is make sure that ΣF=0
What about earthquake dynamics? Got a lot of movement there. Just like Mechanical.
What about expansion of materials due to heat transfer? Sounds a lot like thermo to me.
Also, I don't want to take away from ΣF=0 as it is important, but I could give a determinate structure and ask for forces and most people could solve it. I give an indeterminate framework to someone and very few could do that.