An electric fence won't STOP a bear if it's really determined, but a zap on the nose is a good way to discourage them.
I can't tell where you're from, but I've had some experience with brown bears in AK, and we have some AK people here (I don't live there anymore so I'm a bit unqualified I suppose).
Bears are extremely opportunistic, so if you discourage them right from day one, they will usually quickly move on to greener pastures. A sturdy fence with some strands of electric around it is an excellent way to make them think twice.
A decent building for a coop, should be enough really, they CAN rip siding off, but they don't generally do so if they don't have a good reason to think it's worth their trouble.