12:19 PM PT -- The Steelers announced they have waived Kelly following the arrest.
7:40 AM PT -- Kelly was allegedly punched in the face SEVERAL times by a cop before he was arrested ... according to more details in the court documents.
In the scuffle with officers that ensued after Kelly refused to leave the bar ... the court docs say, a cop needed to punch Kelly "multiple" times to subdue him.
The NFL player -- who suffered a "busted lip" in the scrap -- was taken to UPMC Mercy hospital for treatment, the docs say.
Steelers safety Kameron Kelly was arrested Friday ... after he allegedly made "terroristic threats" during an altercation at a Pittsburgh-area bar.
According to court documents obtained by KDKA, cops were called to Mario’s South Side Saloon after 23-year-old Kelly refused to leave the pub.
Police say Kelly was combative, and after they instructed him to leave the bar area ... he refused -- and still tried to make his way back in.
Cops also say Kelly had threatened a male bar staffer ... saying he would "knock out" the man.
Kelly was eventually arrested ... and according to court docs, he was hit with two misdemeanor charges of terroristic threats and one misdemeanor charge of resisting arrest.
The 6'2", 205-pound DB was slated for a preliminary arraignment hearing in an Allegheny County courtroom Friday.
Kelly has played in 14 games for the Steelers this season ... logging an interception and 21 tackles.
Originally published -- 7:10 AM PT