Place the roast in a dutch oven, add broth, onion, and celery. Bring to a boil, reduce heat, cover and simmer for 2.5-3 hours or until the meat is tender.
Remove the roast and cool slightly, shred the meat with 2 forks. Strain the vegetables and set aside. Skim fat from the cooking liquid and reserve 1.5 cups. Return the meat and vegetables and reserved liquid to the pan.
Stir in ketchup, brown sugar, vinegar, salt, mustard, worcestershire sauce, garlic, bay leaf, garlic powder, paprika, and hot pepper sauce. Bring to a boil. Reduce heat, cover and simmer for 30 minutes. Discard bay leaf. Serve on buns.