The pilot reported that during the landing, he crossed the threshold at 85 to 90 knots with 15 degrees of flaps. The pilot utilized the electric trim as the airplane floated down the runway about 3 to 4 feet above the surface. The airplane subsequently touched down hard and it bounced three times, striking the propeller on the runway each time. The nose gear was damaged and the pilot was unable to maintain directional control with braking action and rudder control. The airplane departed the side of the runway collapsing the landing gear. Postaccident examination of the airplane’s belly revealed that five bulkheads from the firewall aft were bent.