Base reactions Vs. Joint Reactions

[Bigals]

Good day,

I am confused by the meaning of Base reactions, I created a model for a rather simple 1 story 3m high building to which I applied a static lateral load, the resulting BASE reactions were off the wall. So I created an even simpler model with just 1 cantilever beam to which I applied a simple compression force, in joint reactions the reaction was simply the opposite of the force I applied with no moments. However in BASE reactions I get a very high moment? Why is that? What does base reactions stand for?

Thank you
Bigals

 

[ggcdn]

I believe the base reaction is a set of resultant forces about the origin (0,0,0).

If your structure is not at (0,0,0), a simply gravity load will report a base moment.