well congratulations, at least you have control of the situation. And yes violence is never a good solution to problems. Smacking alone is not a creative solution and it is not a univeral panacea but neither is talking a child to death nor is time out nor is removal of privildges.
Also various punishments and discipline methods work on differently on various children, depending on their ages and temperments.
I believe if you only use smacking you are lost. If you only use time out or other isolating punishments etc you are lost, for they only work with the co-operation of the child.
Tell a child that a candle flame will burn them and most children will believe you, and not touch but very few children will stick their finger into a candle flame a second time.
Now we have as our biological duty the responsibilty to raise a socially functional, healthy biologically functioning adult. But they are infants first, then children, then teenagers and then and only then adults, that takes 20 years. We have to do our best to breed'em raise'em then ship'em out. Teaching a person that the world is going to be a gentle kind place is cruelty of the highest order. You step out of line in the world and you are going to get something really hard and heavy slapped on you.
If parents started raising kids to be adults instead of trying to raise friends i think the world would be a better place. Just because you gave birth to them doesn't mean you have to like them nor them you.
My two children were raised with physical discipline along with verbal and other chastisments. They didn't like me at times well tough! But both my adults that i have raised are good strong independant individuals who own their own behavior and with whom we are intergenerational friends.