The pilot stated that he had three passengers onboard and was in contact with air traffic controllers at Charleston Approach. He recalled that the radios began to flicker on and off and radio communication was lost. After checking the voltage he realized that he was having an electric failure. He set the transponder to the emergency code and prepared for a precautionary landing at Berkeley County Airport, Moncks Corner, South Carolina. The pilot stated that during the final approach to landing, he reduced the power to idle and attempted to extended the landing gear. The airplane began to descend rapidly and the pilot added power. The pilot stated," although he added power the airplane continued to descend". He landed approximately 100 feet short of the runway, and collided with ground debris. After the airplane came to a stop the pilot and passengers exited the airplane uninjured. The pilot stated that there were no mechanical or flight control anomalies with the airplane prior to the accident. Examination by an FAA inspector revealed that the wings were separated from the wing roots, and the fuselage was buckled. The landing gear handle, and landing gear was in the up and stowed position. Further examination revealed the alternator tension bolt was loose.