Place ribs in several large roasting pans. Cover and bake at 350° for 1 hour; drain. bake 15-20 minutes longer or until almost tender.
Meanwhile, in a stockpot, combine the barbecue sauce, pineapple, brown sugar and liquid smoke if desired; cook and stir until sugar is dissolved. Drain ribs; pour sauce over ribs. Bake, uncovered, for 15-20 minutes or until tender.