Walaikum Ssalaam Sister,
Thats not good. Hope some ways have been figured to improve the situation at your house. May Allah calm your brother, and show him ways to alter himself from deep within. May he turn to be a pillar of support for your father in his old age .... Ameen.
I have heard of many bullying , physical, violent while kids/teenage , and one fine day they realize there are better ways to get things done, And that changes them for the better. May such a transformation set in your brother too... Ameen
What caused your brother to be thus? Was he always like this? Does he have frustration, disappointment and reasons for getting angry, and is he using violence to solve it? Sometimes situations can make a person go bad. Does he have health problems? Any addiction? Bad company Or is he being stubborn/stupid? Does he talk, exchange views, opinions?
Some sense has to go into his head. Somebody has to drive sense into him, [Insha Allah lets hope mere words would be sufficient]. He has to understand, there is no point in being angry/Violent. I have seen classmates, who when mixed with calm strict students changed their ways. Maybe he should be given some guidance and direction, anger management, new goals in life etc. It takes effort from both sides, no doubt.
You might need the help of someone who is skilled enough to understand your brother and figure the right course of action. I would like to finish saying not all is lost, there is hope for your brother, get the right help... Insha Allah, he will change for better.