Disclosed is a virtually renewable electric power-generating system configured to provide an efficient means for generating electricity for charging an electrical energy storage source such as batteries using the same energy storage source to power an electro-mechanical system for generating electricity. Part of the output of the electro-mechanical system for generating electricity is fed back to the energy storage source to recharge the storage source, as well as provide energy to charge a second energy storage system.

A PC girder bridge structure is constructed by overhanging bridge body blocks formed of cast-in-place concrete or segment blocks from one section to another between bridge piers on the basis of an overhanging erection method. The structure includes concrete blocks formed by rabbeting from one section to another continuously in the longitudinal direction, PC steel members arranged continuously in main girders except for the main girder in a central section, which corresponds to a closure portion between spans. The PC steel members are arranged in the lower portion of the central section so as to penetrate through adjacent sections and continue to the overhanging bridge body blocks of next sections in a curved manner through an upper or lower portions thereof, and the PC steel members disposed in the main girders and the PC steel members arranged in the lower portion of the main girder in the central section are fixed in a strained manner to apply a prestress to the concrete of the main girders.