Most times a quality body shop can repair a bent truck frame with the proper equipment.
I've seen some badly bent truck frames and trailer frames straightened out by a professional auto body repair shop and it was like it never happened.
If the truck frame is severely twisted and really bent then it might not be possible to repair the truck frame and you may have to have a new truck frame fabricated for your truck which can be done by a good body shop and fabrication shop.
I've had a truck frame that was bent really bad but the cab was okay after a wreck and I just found another good truck frame and put my cab on it and it was like it never happened either.
Sometimes truck frames are able to be straightened out and sometimes not and it might be cheaper to find another good use truck frame from a scrap yard.