<p>This Architectural Drawing is AutoCAD, 2d drawing of Expansion of girder details in AutoCAD, dwg file. Girder bridges are the simplest bridge type in structure and consist of <strong>steel beams shaped to an I-section or box section</strong>, called a plate girder bridge or a box girder bridge, respectively. Girder bridges are comprised of deck slabs, on which vehicles and people pass, and of main girders supporting the deck slabs.</p>