COMPOSITE GIRDER STRUCTURE

PROBLEM TO BE SOLVED: To provide a composite girder structure using an I-type steel latticed floor slab, which is lightweight and retains ventilation and drainability, and requires no increase of the sections of main girders. SOLUTION: Main members 21 and side main members 22, both of which are made of I-type steel, are assembled together at a right angle to form the I-type steel latticed floor slab 2, of which the side main members 22 are arranged in parallel to the bridge axis, and the latticed floor slab 2 is joined to only respective upper surfaces 1a of a plurality of main girders 1 via concrete joints 3 to form the composite girder structure. Each upper surface 1a of the main girder is provided with a plurality of stud dowels 11, and respective one bar of side member 22a and 22b are arranged along both side ends of each upper surface 1a. Each set of side members 22a, 22b and each upper surface 1a of the main girder form a recessed space, and a concrete is placed into respective spaces to integrate the I-type steel latticed floor slab 2 and each main girder 1 together.