Composite floor structure using two precast composite steel beams with web openings and the construction method

A composite floor plate structure using a precast composite beam including a pair of steel beams having through holes on a web is provided to utilize the advantages of a slim floor system for a long span by increasing stiffness and reducing vibration and deflection, to secure an access floor space sufficiently, to install an underfloor air distribution system in an access floor space easily by reducing the thickness of a floor plate of a composite floor plate effectively and to fulfill the function of various floor plates by securing an installation space for the upper floor easily. A composite floor plate structure using a precast composite beam including a pair of steel beams having through holes on a web includes a precast composite beam composed of a pair of steel beams(200) provided with many through holes on a web and arranged in a row at a certain distance, tension plates(250) unified with a lower flange between lower flanges of a pair of the steel beams, and, bordered on the entire bottom of the lower flanges, and filler(260) including concrete placed and cured in the inside closed space formed by the continued tension plates and a pair of the steel beams, a floor plate unit(100) including a deck installed on the top of the lower flange of the steel beam of the precast composite beam or the web spaced out from the top of the lower flange, and floor plate concrete buried with upper reinforcing bars arranged in the floor plate unit continuously via the through holes of the steel beam and connected with the through holes.