Is it normal for an advisor to expect >80 hour workweeks from PhD students, and threaten them with dismissal? My advisor always keeps pointing out that I should have publications and I should keep working and stuff like that. Recently he's been saying that not all student will finish Ph.D. and you should be careful not to be kicked out. He has this notion that Ph.D. students should work more than 80 hours per week on regular basis and near deadlines even they should cut off from their sleep time. I get the idea that he wants to encourage me and I also know that as a Ph.D student I need to have publications.

Is this type of behavior common among most advisors? Is it common for Ph.D. students to be expected to not have a life and just work? And finally do all advisors keep threatening their students like this?

I'm currently a second year computer science student. I've been accepted by the department, not a specific faculty member. Also my funding is coming from TAship not his grant.  I'm not sure if I should start looking for another advisor, because I'm not sure whether the behavior I have described is normal.
I'm sure some advisors do act this way.  I don't think it's very common, but it does happen.  It's more common for advisors to expect certain results than a particular hourly commitment, but all these things are a matter of extent.

However, in trying to figure out whether to switch advisors, I think you're asking yourself the wrong question.  The right question is: 


  What type of advising relationship works for you?


If you feel energized, motivated, and happy under your current conditions, that's one thing.  If you feel overburdened and miserable, then you should probably look for a different advisor.  Even the most competitive Ph.D. programs have faculty who are not so demanding.  You have to figure out what type of style works best for you and try to find an advisor who is a good match.